Ramsey classes - math.wisc.edulempp/conf/asl12//Slides/Sokic.pdf · Introduction Motivation...
Transcript of Ramsey classes - math.wisc.edulempp/conf/asl12//Slides/Sokic.pdf · Introduction Motivation...
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Ramseyclasses
Miodrag Sokic
IntroductionMotivationTopologicaldynamicsModel theoryRamsey theoryThe KPT theory
QuestionsPosetsUltrametricspaces
ResultsPosetsUltrametric
IntroductionQuestionsResults
Ramsey classes
Miodrag Sokic
Caltech
April 1st 2012, Madison
Miodrag Sokic Ramsey classes
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Ramseyclasses
Miodrag Sokic
IntroductionMotivationTopologicaldynamicsModel theoryRamsey theoryThe KPT theory
QuestionsPosetsUltrametricspaces
ResultsPosetsUltrametric
IntroductionQuestionsResults
MotivationTopological dynamicsModel theoryRamsey theoryThe KPT theory
Motivation
topological dynamics
model theory
combinatorics
KPT
group actions on compact spaces
Fraïssé theory
Ramsey theory
Miodrag Sokic Ramsey classes
![Page 3: Ramsey classes - math.wisc.edulempp/conf/asl12//Slides/Sokic.pdf · Introduction Motivation Topological dynamics Model theory Ramsey theory The KPT theory Questions Posets Ultrametric](https://reader033.fdocuments.in/reader033/viewer/2022042417/5f32e8bcce0604000a3fd15f/html5/thumbnails/3.jpg)
Ramseyclasses
Miodrag Sokic
IntroductionMotivationTopologicaldynamicsModel theoryRamsey theoryThe KPT theory
QuestionsPosetsUltrametricspaces
ResultsPosetsUltrametric
IntroductionQuestionsResults
MotivationTopological dynamicsModel theoryRamsey theoryThe KPT theory
Motivation
topological dynamics
model theory
combinatorics
KPT
group actions on compact spaces
Fraïssé theory
Ramsey theory
Miodrag Sokic Ramsey classes
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Ramseyclasses
Miodrag Sokic
IntroductionMotivationTopologicaldynamicsModel theoryRamsey theoryThe KPT theory
QuestionsPosetsUltrametricspaces
ResultsPosetsUltrametric
IntroductionQuestionsResults
MotivationTopological dynamicsModel theoryRamsey theoryThe KPT theory
Motivation
topological dynamics
model theory
combinatorics
KPT
group actions on compact spaces
Fraïssé theory
Ramsey theory
Miodrag Sokic Ramsey classes
![Page 5: Ramsey classes - math.wisc.edulempp/conf/asl12//Slides/Sokic.pdf · Introduction Motivation Topological dynamics Model theory Ramsey theory The KPT theory Questions Posets Ultrametric](https://reader033.fdocuments.in/reader033/viewer/2022042417/5f32e8bcce0604000a3fd15f/html5/thumbnails/5.jpg)
Ramseyclasses
Miodrag Sokic
IntroductionMotivationTopologicaldynamicsModel theoryRamsey theoryThe KPT theory
QuestionsPosetsUltrametricspaces
ResultsPosetsUltrametric
IntroductionQuestionsResults
MotivationTopological dynamicsModel theoryRamsey theoryThe KPT theory
Motivation
topological dynamics
model theory
combinatorics
KPT
group actions on compact spaces
Fraïssé theory
Ramsey theory
Miodrag Sokic Ramsey classes
![Page 6: Ramsey classes - math.wisc.edulempp/conf/asl12//Slides/Sokic.pdf · Introduction Motivation Topological dynamics Model theory Ramsey theory The KPT theory Questions Posets Ultrametric](https://reader033.fdocuments.in/reader033/viewer/2022042417/5f32e8bcce0604000a3fd15f/html5/thumbnails/6.jpg)
Ramseyclasses
Miodrag Sokic
IntroductionMotivationTopologicaldynamicsModel theoryRamsey theoryThe KPT theory
QuestionsPosetsUltrametricspaces
ResultsPosetsUltrametric
IntroductionQuestionsResults
MotivationTopological dynamicsModel theoryRamsey theoryThe KPT theory
Motivation
topological dynamics
model theory
combinatorics
KPT
group actions on compact spaces
Fraïssé theory
Ramsey theory
Miodrag Sokic Ramsey classes
![Page 7: Ramsey classes - math.wisc.edulempp/conf/asl12//Slides/Sokic.pdf · Introduction Motivation Topological dynamics Model theory Ramsey theory The KPT theory Questions Posets Ultrametric](https://reader033.fdocuments.in/reader033/viewer/2022042417/5f32e8bcce0604000a3fd15f/html5/thumbnails/7.jpg)
Ramseyclasses
Miodrag Sokic
IntroductionMotivationTopologicaldynamicsModel theoryRamsey theoryThe KPT theory
QuestionsPosetsUltrametricspaces
ResultsPosetsUltrametric
IntroductionQuestionsResults
MotivationTopological dynamicsModel theoryRamsey theoryThe KPT theory
Motivation
topological dynamics
model theory
combinatorics
KPT
group actions on compact spaces
Fraïssé theory
Ramsey theory
Miodrag Sokic Ramsey classes
![Page 8: Ramsey classes - math.wisc.edulempp/conf/asl12//Slides/Sokic.pdf · Introduction Motivation Topological dynamics Model theory Ramsey theory The KPT theory Questions Posets Ultrametric](https://reader033.fdocuments.in/reader033/viewer/2022042417/5f32e8bcce0604000a3fd15f/html5/thumbnails/8.jpg)
Ramseyclasses
Miodrag Sokic
IntroductionMotivationTopologicaldynamicsModel theoryRamsey theoryThe KPT theory
QuestionsPosetsUltrametricspaces
ResultsPosetsUltrametric
IntroductionQuestionsResults
MotivationTopological dynamicsModel theoryRamsey theoryThe KPT theory
Motivation
topological dynamics
model theory
combinatorics
KPT
group actions on compact spaces
Fraïssé theory
Ramsey theory
Miodrag Sokic Ramsey classes
![Page 9: Ramsey classes - math.wisc.edulempp/conf/asl12//Slides/Sokic.pdf · Introduction Motivation Topological dynamics Model theory Ramsey theory The KPT theory Questions Posets Ultrametric](https://reader033.fdocuments.in/reader033/viewer/2022042417/5f32e8bcce0604000a3fd15f/html5/thumbnails/9.jpg)
Ramseyclasses
Miodrag Sokic
IntroductionMotivationTopologicaldynamicsModel theoryRamsey theoryThe KPT theory
QuestionsPosetsUltrametricspaces
ResultsPosetsUltrametric
IntroductionQuestionsResults
MotivationTopological dynamicsModel theoryRamsey theoryThe KPT theory
Topological dynamics
G-�ow continuous action on a compact
Hausdor¤ space
G� X ! X
minimal �ow for all x 2 X
G � x = X
FactEvery G-�ow contains a minimal sub�ow.
Miodrag Sokic Ramsey classes
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Ramseyclasses
Miodrag Sokic
IntroductionMotivationTopologicaldynamicsModel theoryRamsey theoryThe KPT theory
QuestionsPosetsUltrametricspaces
ResultsPosetsUltrametric
IntroductionQuestionsResults
MotivationTopological dynamicsModel theoryRamsey theoryThe KPT theory
Topological dynamics
G-�ow continuous action on a compact
Hausdor¤ space
G� X ! X
minimal �ow for all x 2 X
G � x = X
FactEvery G-�ow contains a minimal sub�ow.
Miodrag Sokic Ramsey classes
![Page 11: Ramsey classes - math.wisc.edulempp/conf/asl12//Slides/Sokic.pdf · Introduction Motivation Topological dynamics Model theory Ramsey theory The KPT theory Questions Posets Ultrametric](https://reader033.fdocuments.in/reader033/viewer/2022042417/5f32e8bcce0604000a3fd15f/html5/thumbnails/11.jpg)
Ramseyclasses
Miodrag Sokic
IntroductionMotivationTopologicaldynamicsModel theoryRamsey theoryThe KPT theory
QuestionsPosetsUltrametricspaces
ResultsPosetsUltrametric
IntroductionQuestionsResults
MotivationTopological dynamicsModel theoryRamsey theoryThe KPT theory
Topological dynamics
G-�ow continuous action on a compact
Hausdor¤ space
G� X ! X
minimal �ow for all x 2 X
G � x = X
FactEvery G-�ow contains a minimal sub�ow.
Miodrag Sokic Ramsey classes
![Page 12: Ramsey classes - math.wisc.edulempp/conf/asl12//Slides/Sokic.pdf · Introduction Motivation Topological dynamics Model theory Ramsey theory The KPT theory Questions Posets Ultrametric](https://reader033.fdocuments.in/reader033/viewer/2022042417/5f32e8bcce0604000a3fd15f/html5/thumbnails/12.jpg)
Ramseyclasses
Miodrag Sokic
IntroductionMotivationTopologicaldynamicsModel theoryRamsey theoryThe KPT theory
QuestionsPosetsUltrametricspaces
ResultsPosetsUltrametric
IntroductionQuestionsResults
MotivationTopological dynamicsModel theoryRamsey theoryThe KPT theory
Topological dynamics
Theorem
Given a topological group G, there is a minimal G-�ow M(G)such that for any other minimal G-�ow Y there exists surjectivehomomorphism
ϕ : M(G)! Yϕ(gx) = gϕ(x)
Moreover such G-�ow M(G) is uniquely determined up toisomorphism.
Miodrag Sokic Ramsey classes
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Ramseyclasses
Miodrag Sokic
IntroductionMotivationTopologicaldynamicsModel theoryRamsey theoryThe KPT theory
QuestionsPosetsUltrametricspaces
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IntroductionQuestionsResults
MotivationTopological dynamicsModel theoryRamsey theoryThe KPT theory
Topological dynamics
The minimal G-�ow M(G) established in the previous theoremis called the universal minimal G-�ow.
A group G is extremely amenable(has �xed point on compactaproperty) if M(G) = f�g.
Miodrag Sokic Ramsey classes
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Ramseyclasses
Miodrag Sokic
IntroductionMotivationTopologicaldynamicsModel theoryRamsey theoryThe KPT theory
QuestionsPosetsUltrametricspaces
ResultsPosetsUltrametric
IntroductionQuestionsResults
MotivationTopological dynamicsModel theoryRamsey theoryThe KPT theory
Topological dynamics
The minimal G-�ow M(G) established in the previous theoremis called the universal minimal G-�ow.A group G is extremely amenable(has �xed point on compactaproperty) if M(G) = f�g.
Miodrag Sokic Ramsey classes
![Page 15: Ramsey classes - math.wisc.edulempp/conf/asl12//Slides/Sokic.pdf · Introduction Motivation Topological dynamics Model theory Ramsey theory The KPT theory Questions Posets Ultrametric](https://reader033.fdocuments.in/reader033/viewer/2022042417/5f32e8bcce0604000a3fd15f/html5/thumbnails/15.jpg)
Ramseyclasses
Miodrag Sokic
IntroductionMotivationTopologicaldynamicsModel theoryRamsey theoryThe KPT theory
QuestionsPosetsUltrametricspaces
ResultsPosetsUltrametric
IntroductionQuestionsResults
MotivationTopological dynamicsModel theoryRamsey theoryThe KPT theory
Fraïssé classes
K-class of �nite structures in a countable signature L, closedunder isomorphic imagesFraïssé class
contains structures of arbitrary large �nite cardinality
hereditary property (HP) A ,! B 2 K =) A 2 Kjoint embedding property (JEP) (8A, B 2 K)(9C 2 K)[A ,! C & B ,! C]amalgamation property (AP) (8A, B, C 2 K)(8f : A! B, g : A! C)(9D 2 K)(9f 0 : B! D, g0 : C! D)[ f 0 � f = g0 � g]
Miodrag Sokic Ramsey classes
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Ramseyclasses
Miodrag Sokic
IntroductionMotivationTopologicaldynamicsModel theoryRamsey theoryThe KPT theory
QuestionsPosetsUltrametricspaces
ResultsPosetsUltrametric
IntroductionQuestionsResults
MotivationTopological dynamicsModel theoryRamsey theoryThe KPT theory
Fraïssé classes
K-class of �nite structures in a countable signature L, closedunder isomorphic imagesFraïssé class
contains structures of arbitrary large �nite cardinality
hereditary property (HP) A ,! B 2 K =) A 2 K
joint embedding property (JEP) (8A, B 2 K)(9C 2 K)[A ,! C & B ,! C]amalgamation property (AP) (8A, B, C 2 K)(8f : A! B, g : A! C)(9D 2 K)(9f 0 : B! D, g0 : C! D)[ f 0 � f = g0 � g]
Miodrag Sokic Ramsey classes
![Page 17: Ramsey classes - math.wisc.edulempp/conf/asl12//Slides/Sokic.pdf · Introduction Motivation Topological dynamics Model theory Ramsey theory The KPT theory Questions Posets Ultrametric](https://reader033.fdocuments.in/reader033/viewer/2022042417/5f32e8bcce0604000a3fd15f/html5/thumbnails/17.jpg)
Ramseyclasses
Miodrag Sokic
IntroductionMotivationTopologicaldynamicsModel theoryRamsey theoryThe KPT theory
QuestionsPosetsUltrametricspaces
ResultsPosetsUltrametric
IntroductionQuestionsResults
MotivationTopological dynamicsModel theoryRamsey theoryThe KPT theory
Fraïssé classes
K-class of �nite structures in a countable signature L, closedunder isomorphic imagesFraïssé class
contains structures of arbitrary large �nite cardinality
hereditary property (HP) A ,! B 2 K =) A 2 Kjoint embedding property (JEP) (8A, B 2 K)(9C 2 K)[A ,! C & B ,! C]
amalgamation property (AP) (8A, B, C 2 K)(8f : A! B, g : A! C)(9D 2 K)(9f 0 : B! D, g0 : C! D)[ f 0 � f = g0 � g]
Miodrag Sokic Ramsey classes
![Page 18: Ramsey classes - math.wisc.edulempp/conf/asl12//Slides/Sokic.pdf · Introduction Motivation Topological dynamics Model theory Ramsey theory The KPT theory Questions Posets Ultrametric](https://reader033.fdocuments.in/reader033/viewer/2022042417/5f32e8bcce0604000a3fd15f/html5/thumbnails/18.jpg)
Ramseyclasses
Miodrag Sokic
IntroductionMotivationTopologicaldynamicsModel theoryRamsey theoryThe KPT theory
QuestionsPosetsUltrametricspaces
ResultsPosetsUltrametric
IntroductionQuestionsResults
MotivationTopological dynamicsModel theoryRamsey theoryThe KPT theory
Fraïssé classes
K-class of �nite structures in a countable signature L, closedunder isomorphic imagesFraïssé class
contains structures of arbitrary large �nite cardinality
hereditary property (HP) A ,! B 2 K =) A 2 Kjoint embedding property (JEP) (8A, B 2 K)(9C 2 K)[A ,! C & B ,! C]amalgamation property (AP) (8A, B, C 2 K)(8f : A! B, g : A! C)(9D 2 K)(9f 0 : B! D, g0 : C! D)[ f 0 � f = g0 � g]
Miodrag Sokic Ramsey classes
![Page 19: Ramsey classes - math.wisc.edulempp/conf/asl12//Slides/Sokic.pdf · Introduction Motivation Topological dynamics Model theory Ramsey theory The KPT theory Questions Posets Ultrametric](https://reader033.fdocuments.in/reader033/viewer/2022042417/5f32e8bcce0604000a3fd15f/html5/thumbnails/19.jpg)
Ramseyclasses
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QuestionsPosetsUltrametricspaces
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IntroductionQuestionsResults
MotivationTopological dynamicsModel theoryRamsey theoryThe KPT theory
Fraïssé structures
Fraïssé structure (countable signature L)
in�nite countable
locally �nite-every �nitely generated substructure is �nite
ultrahomogeneous-any isomorphism between two �nitesubstructures can be extended to (global) automorphism
Age(A)-(age)class of �nite structures embedable into A
Miodrag Sokic Ramsey classes
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Ramseyclasses
Miodrag Sokic
IntroductionMotivationTopologicaldynamicsModel theoryRamsey theoryThe KPT theory
QuestionsPosetsUltrametricspaces
ResultsPosetsUltrametric
IntroductionQuestionsResults
MotivationTopological dynamicsModel theoryRamsey theoryThe KPT theory
Fraïssé structures
Fraïssé structure (countable signature L)
in�nite countable
locally �nite-every �nitely generated substructure is �nite
ultrahomogeneous-any isomorphism between two �nitesubstructures can be extended to (global) automorphism
Age(A)-(age)class of �nite structures embedable into A
Miodrag Sokic Ramsey classes
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Ramseyclasses
Miodrag Sokic
IntroductionMotivationTopologicaldynamicsModel theoryRamsey theoryThe KPT theory
QuestionsPosetsUltrametricspaces
ResultsPosetsUltrametric
IntroductionQuestionsResults
MotivationTopological dynamicsModel theoryRamsey theoryThe KPT theory
Fraïssé structures
Fraïssé structure (countable signature L)
in�nite countable
locally �nite-every �nitely generated substructure is �nite
ultrahomogeneous-any isomorphism between two �nitesubstructures can be extended to (global) automorphism
Age(A)-(age)class of �nite structures embedable into A
Miodrag Sokic Ramsey classes
![Page 22: Ramsey classes - math.wisc.edulempp/conf/asl12//Slides/Sokic.pdf · Introduction Motivation Topological dynamics Model theory Ramsey theory The KPT theory Questions Posets Ultrametric](https://reader033.fdocuments.in/reader033/viewer/2022042417/5f32e8bcce0604000a3fd15f/html5/thumbnails/22.jpg)
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"1-1"
Theorem
Let K be a Fraïssé class. Then there is a unique, up toisomorphism, Fraïssé structure K such that K = Age(K).
Fraïssé limit-K =F lim(K)
Theorem
Let K be a Fraïssé structure. Then Age(K) is a Fraïssé class.
For every Fraïssé structure K we consider its automorphismgroup Aut(K) with pointwise convergence topology,it is aPolish group.
Miodrag Sokic Ramsey classes
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Ramseyclasses
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QuestionsPosetsUltrametricspaces
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MotivationTopological dynamicsModel theoryRamsey theoryThe KPT theory
"1-1"
Theorem
Let K be a Fraïssé class. Then there is a unique, up toisomorphism, Fraïssé structure K such that K = Age(K).
Fraïssé limit-K =F lim(K)
Theorem
Let K be a Fraïssé structure. Then Age(K) is a Fraïssé class.
For every Fraïssé structure K we consider its automorphismgroup Aut(K) with pointwise convergence topology,it is aPolish group.
Miodrag Sokic Ramsey classes
![Page 24: Ramsey classes - math.wisc.edulempp/conf/asl12//Slides/Sokic.pdf · Introduction Motivation Topological dynamics Model theory Ramsey theory The KPT theory Questions Posets Ultrametric](https://reader033.fdocuments.in/reader033/viewer/2022042417/5f32e8bcce0604000a3fd15f/html5/thumbnails/24.jpg)
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MotivationTopological dynamicsModel theoryRamsey theoryThe KPT theory
"1-1"
Theorem
Let K be a Fraïssé class. Then there is a unique, up toisomorphism, Fraïssé structure K such that K = Age(K).
Fraïssé limit-K =F lim(K)
Theorem
Let K be a Fraïssé structure. Then Age(K) is a Fraïssé class.
For every Fraïssé structure K we consider its automorphismgroup Aut(K) with pointwise convergence topology,it is aPolish group.
Miodrag Sokic Ramsey classes
![Page 25: Ramsey classes - math.wisc.edulempp/conf/asl12//Slides/Sokic.pdf · Introduction Motivation Topological dynamics Model theory Ramsey theory The KPT theory Questions Posets Ultrametric](https://reader033.fdocuments.in/reader033/viewer/2022042417/5f32e8bcce0604000a3fd15f/html5/thumbnails/25.jpg)
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Arrow notation
K-class of �nite structures in signature L
For A, B 2K we write:�BA
�= fC � B : C u Ag.
Let A, B, C 2K. If for any coloringc : (C
A)! f1, .., rg,there exist a structure B0 2 (C
B) such that
c ��
B0
A
�= const
then we writeC! (B)A
r .
Miodrag Sokic Ramsey classes
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MotivationTopological dynamicsModel theoryRamsey theoryThe KPT theory
Arrow notation
K-class of �nite structures in signature LFor A, B 2K we write:�
BA
�= fC � B : C u Ag.
Let A, B, C 2K. If for any coloringc : (C
A)! f1, .., rg,there exist a structure B0 2 (C
B) such that
c ��
B0
A
�= const
then we writeC! (B)A
r .
Miodrag Sokic Ramsey classes
![Page 27: Ramsey classes - math.wisc.edulempp/conf/asl12//Slides/Sokic.pdf · Introduction Motivation Topological dynamics Model theory Ramsey theory The KPT theory Questions Posets Ultrametric](https://reader033.fdocuments.in/reader033/viewer/2022042417/5f32e8bcce0604000a3fd15f/html5/thumbnails/27.jpg)
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Miodrag Sokic
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QuestionsPosetsUltrametricspaces
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IntroductionQuestionsResults
MotivationTopological dynamicsModel theoryRamsey theoryThe KPT theory
Arrow notation
K-class of �nite structures in signature LFor A, B 2K we write:�
BA
�= fC � B : C u Ag.
Let A, B, C 2K. If for any coloringc : (C
A)! f1, .., rg,there exist a structure B0 2 (C
B) such that
c ��
B0
A
�= const
then we writeC! (B)A
r .
Miodrag Sokic Ramsey classes
![Page 28: Ramsey classes - math.wisc.edulempp/conf/asl12//Slides/Sokic.pdf · Introduction Motivation Topological dynamics Model theory Ramsey theory The KPT theory Questions Posets Ultrametric](https://reader033.fdocuments.in/reader033/viewer/2022042417/5f32e8bcce0604000a3fd15f/html5/thumbnails/28.jpg)
Ramseyclasses
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Ramsey degree
Let K be a class of �nite structures. If for natural numbers rand t and structures A, B and C from K we have that forevery coloring
c :�
C
A
�! f1, ..., rg,
there is B0 2 (CB) such that c � (B0
A) takes at most t many
values then we writeC! (B)Ar,t.
We say that A 2 K has the Ramsey degree t if for everyB 2K and every natural number r there is C 2K such thatC! (B)Ar,t and t is the smallest such number. We denote sucha number by tK(A).Note that K is a Ramsey class i¤ tK(A) = 1 for all A 2K.
Miodrag Sokic Ramsey classes
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(Kechris-Pestov-Todorµcevic 2005)
TheoremFor ordered classes
RP ! extreme amenability,(RP for K) ! Aut(F lim(K)).
Theorem
(RP+OP) ! universal minimal �ow,(RP for K+OP for OK) !
universal minimal �ow Aut(F lim(K)).
Miodrag Sokic Ramsey classes
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(Kechris-Pestov-Todorµcevic 2005)
TheoremFor ordered classes
RP ! extreme amenability,(RP for K) ! Aut(F lim(K)).
Theorem
(RP+OP) ! universal minimal �ow,(RP for K+OP for OK) !
universal minimal �ow Aut(F lim(K)).
Miodrag Sokic Ramsey classes
![Page 31: Ramsey classes - math.wisc.edulempp/conf/asl12//Slides/Sokic.pdf · Introduction Motivation Topological dynamics Model theory Ramsey theory The KPT theory Questions Posets Ultrametric](https://reader033.fdocuments.in/reader033/viewer/2022042417/5f32e8bcce0604000a3fd15f/html5/thumbnails/31.jpg)
Ramseyclasses
Miodrag Sokic
IntroductionMotivationTopologicaldynamicsModel theoryRamsey theoryThe KPT theory
QuestionsPosetsUltrametricspaces
ResultsPosetsUltrametric
IntroductionQuestionsResults
PosetsUltrametric spaces
Posets
Let P be the class of �nite posets.If we add arbitrary linear orderings to posets:
OP = f(A,v,�) : (A,v) 2 P & �2 lo(A)g.
If we add only linear extensions of partial orderings:
EP = f(A,v,�) 2 OP :�2 le(v)g.
Miodrag Sokic Ramsey classes
![Page 32: Ramsey classes - math.wisc.edulempp/conf/asl12//Slides/Sokic.pdf · Introduction Motivation Topological dynamics Model theory Ramsey theory The KPT theory Questions Posets Ultrametric](https://reader033.fdocuments.in/reader033/viewer/2022042417/5f32e8bcce0604000a3fd15f/html5/thumbnails/32.jpg)
Ramseyclasses
Miodrag Sokic
IntroductionMotivationTopologicaldynamicsModel theoryRamsey theoryThe KPT theory
QuestionsPosetsUltrametricspaces
ResultsPosetsUltrametric
IntroductionQuestionsResults
PosetsUltrametric spaces
Limits
Fraïssé limits of posets:
Random poset P = F lim(P),Random poset with linear extension EP = F lim(EP),Random poset with random ordering OP = F lim(OP).
Miodrag Sokic Ramsey classes
![Page 33: Ramsey classes - math.wisc.edulempp/conf/asl12//Slides/Sokic.pdf · Introduction Motivation Topological dynamics Model theory Ramsey theory The KPT theory Questions Posets Ultrametric](https://reader033.fdocuments.in/reader033/viewer/2022042417/5f32e8bcce0604000a3fd15f/html5/thumbnails/33.jpg)
Ramseyclasses
Miodrag Sokic
IntroductionMotivationTopologicaldynamicsModel theoryRamsey theoryThe KPT theory
QuestionsPosetsUltrametricspaces
ResultsPosetsUltrametric
IntroductionQuestionsResults
PosetsUltrametric spaces
Problems
UMF for Aut(P) isknown.
Aut(EP) is extremelyamenable.
Ramsey degree forelements in P is known.EP is a Ramsey class.OP is not a Ramseyclass.
Calculate UMF forAut(OP).
Calculate Ramsey degreesfor objects in OP .
Miodrag Sokic Ramsey classes
![Page 34: Ramsey classes - math.wisc.edulempp/conf/asl12//Slides/Sokic.pdf · Introduction Motivation Topological dynamics Model theory Ramsey theory The KPT theory Questions Posets Ultrametric](https://reader033.fdocuments.in/reader033/viewer/2022042417/5f32e8bcce0604000a3fd15f/html5/thumbnails/34.jpg)
Ramseyclasses
Miodrag Sokic
IntroductionMotivationTopologicaldynamicsModel theoryRamsey theoryThe KPT theory
QuestionsPosetsUltrametricspaces
ResultsPosetsUltrametric
IntroductionQuestionsResults
PosetsUltrametric spaces
Problems
UMF for Aut(P) isknown.
Aut(EP) is extremelyamenable.
Ramsey degree forelements in P is known.EP is a Ramsey class.OP is not a Ramseyclass.
Calculate UMF forAut(OP).
Calculate Ramsey degreesfor objects in OP .
Miodrag Sokic Ramsey classes
![Page 35: Ramsey classes - math.wisc.edulempp/conf/asl12//Slides/Sokic.pdf · Introduction Motivation Topological dynamics Model theory Ramsey theory The KPT theory Questions Posets Ultrametric](https://reader033.fdocuments.in/reader033/viewer/2022042417/5f32e8bcce0604000a3fd15f/html5/thumbnails/35.jpg)
Ramseyclasses
Miodrag Sokic
IntroductionMotivationTopologicaldynamicsModel theoryRamsey theoryThe KPT theory
QuestionsPosetsUltrametricspaces
ResultsPosetsUltrametric
IntroductionQuestionsResults
PosetsUltrametric spaces
Problems
UMF for Aut(P) isknown.
Aut(EP) is extremelyamenable.
Ramsey degree forelements in P is known.EP is a Ramsey class.OP is not a Ramseyclass.
Calculate UMF forAut(OP).
Calculate Ramsey degreesfor objects in OP .
Miodrag Sokic Ramsey classes
![Page 36: Ramsey classes - math.wisc.edulempp/conf/asl12//Slides/Sokic.pdf · Introduction Motivation Topological dynamics Model theory Ramsey theory The KPT theory Questions Posets Ultrametric](https://reader033.fdocuments.in/reader033/viewer/2022042417/5f32e8bcce0604000a3fd15f/html5/thumbnails/36.jpg)
Ramseyclasses
Miodrag Sokic
IntroductionMotivationTopologicaldynamicsModel theoryRamsey theoryThe KPT theory
QuestionsPosetsUltrametricspaces
ResultsPosetsUltrametric
IntroductionQuestionsResults
PosetsUltrametric spaces
Ultrametric
A metric d on a set X is an ultrametric if for all x, y, z 2 X wehave
d(x, z) � maxfd(x, y), d(y, z)g.The spectrum of a metric space X = (X, d) is the set
Spec(X) = fd(x, y) : x 2 X, y 2 X, x 6= yg.
We denote the class of �nite ultrametric spaces by U , and forS � (0,+∞), we consider the class
US = fX 2U : Spec(X) � Sg.
Miodrag Sokic Ramsey classes
![Page 37: Ramsey classes - math.wisc.edulempp/conf/asl12//Slides/Sokic.pdf · Introduction Motivation Topological dynamics Model theory Ramsey theory The KPT theory Questions Posets Ultrametric](https://reader033.fdocuments.in/reader033/viewer/2022042417/5f32e8bcce0604000a3fd15f/html5/thumbnails/37.jpg)
Ramseyclasses
Miodrag Sokic
IntroductionMotivationTopologicaldynamicsModel theoryRamsey theoryThe KPT theory
QuestionsPosetsUltrametricspaces
ResultsPosetsUltrametric
IntroductionQuestionsResults
PosetsUltrametric spaces
Ordered spaces
Linearly ordered ultrametric spaces with distances in the set S :
OU S = f(X, d,� ) : (X, d) 2 US & �2 lo(X)g.
If (X, d,� ) 2OU S and for all x, y, z 2 X we have
x � y � z =) d(x, y) � d(x, z),
then we say that the linear ordering � is convex on theultrametric space (X, d).In the convex linear ordering every ball is an interval withrespect to the linear ordering.The class of all convex linear orderings of an ultrametric spaceX = (X, d) we denote by co(X), and we consider:
CU S = f(X, d,� ) 2OU S : �2 co((X, d))g
Miodrag Sokic Ramsey classes
![Page 38: Ramsey classes - math.wisc.edulempp/conf/asl12//Slides/Sokic.pdf · Introduction Motivation Topological dynamics Model theory Ramsey theory The KPT theory Questions Posets Ultrametric](https://reader033.fdocuments.in/reader033/viewer/2022042417/5f32e8bcce0604000a3fd15f/html5/thumbnails/38.jpg)
Ramseyclasses
Miodrag Sokic
IntroductionMotivationTopologicaldynamicsModel theoryRamsey theoryThe KPT theory
QuestionsPosetsUltrametricspaces
ResultsPosetsUltrametric
IntroductionQuestionsResults
PosetsUltrametric spaces
Ordered spaces
Linearly ordered ultrametric spaces with distances in the set S :
OU S = f(X, d,� ) : (X, d) 2 US & �2 lo(X)g.
If (X, d,� ) 2OU S and for all x, y, z 2 X we have
x � y � z =) d(x, y) � d(x, z),
then we say that the linear ordering � is convex on theultrametric space (X, d).
In the convex linear ordering every ball is an interval withrespect to the linear ordering.The class of all convex linear orderings of an ultrametric spaceX = (X, d) we denote by co(X), and we consider:
CU S = f(X, d,� ) 2OU S : �2 co((X, d))g
Miodrag Sokic Ramsey classes
![Page 39: Ramsey classes - math.wisc.edulempp/conf/asl12//Slides/Sokic.pdf · Introduction Motivation Topological dynamics Model theory Ramsey theory The KPT theory Questions Posets Ultrametric](https://reader033.fdocuments.in/reader033/viewer/2022042417/5f32e8bcce0604000a3fd15f/html5/thumbnails/39.jpg)
Ramseyclasses
Miodrag Sokic
IntroductionMotivationTopologicaldynamicsModel theoryRamsey theoryThe KPT theory
QuestionsPosetsUltrametricspaces
ResultsPosetsUltrametric
IntroductionQuestionsResults
PosetsUltrametric spaces
Ordered spaces
Linearly ordered ultrametric spaces with distances in the set S :
OU S = f(X, d,� ) : (X, d) 2 US & �2 lo(X)g.
If (X, d,� ) 2OU S and for all x, y, z 2 X we have
x � y � z =) d(x, y) � d(x, z),
then we say that the linear ordering � is convex on theultrametric space (X, d).In the convex linear ordering every ball is an interval withrespect to the linear ordering.
The class of all convex linear orderings of an ultrametric spaceX = (X, d) we denote by co(X), and we consider:
CU S = f(X, d,� ) 2OU S : �2 co((X, d))g
Miodrag Sokic Ramsey classes
![Page 40: Ramsey classes - math.wisc.edulempp/conf/asl12//Slides/Sokic.pdf · Introduction Motivation Topological dynamics Model theory Ramsey theory The KPT theory Questions Posets Ultrametric](https://reader033.fdocuments.in/reader033/viewer/2022042417/5f32e8bcce0604000a3fd15f/html5/thumbnails/40.jpg)
Ramseyclasses
Miodrag Sokic
IntroductionMotivationTopologicaldynamicsModel theoryRamsey theoryThe KPT theory
QuestionsPosetsUltrametricspaces
ResultsPosetsUltrametric
IntroductionQuestionsResults
PosetsUltrametric spaces
Ordered spaces
Linearly ordered ultrametric spaces with distances in the set S :
OU S = f(X, d,� ) : (X, d) 2 US & �2 lo(X)g.
If (X, d,� ) 2OU S and for all x, y, z 2 X we have
x � y � z =) d(x, y) � d(x, z),
then we say that the linear ordering � is convex on theultrametric space (X, d).In the convex linear ordering every ball is an interval withrespect to the linear ordering.The class of all convex linear orderings of an ultrametric spaceX = (X, d) we denote by co(X), and we consider:
CU S = f(X, d,� ) 2OU S : �2 co((X, d))g
Miodrag Sokic Ramsey classes
![Page 41: Ramsey classes - math.wisc.edulempp/conf/asl12//Slides/Sokic.pdf · Introduction Motivation Topological dynamics Model theory Ramsey theory The KPT theory Questions Posets Ultrametric](https://reader033.fdocuments.in/reader033/viewer/2022042417/5f32e8bcce0604000a3fd15f/html5/thumbnails/41.jpg)
Ramseyclasses
Miodrag Sokic
IntroductionMotivationTopologicaldynamicsModel theoryRamsey theoryThe KPT theory
QuestionsPosetsUltrametricspaces
ResultsPosetsUltrametric
IntroductionQuestionsResults
PosetsUltrametric spaces
Limits
Fraïssé limits of ultrametric spaces when S is countable:
Random ultrametric space with spectrumS:US = F lim(US).
Random convexly ordered ultrametric space with spectrumS: CUS = F lim(CU S).
Random ordered ultrametric space with spectrum S:OUS = F lim(OU S).
Miodrag Sokic Ramsey classes
![Page 42: Ramsey classes - math.wisc.edulempp/conf/asl12//Slides/Sokic.pdf · Introduction Motivation Topological dynamics Model theory Ramsey theory The KPT theory Questions Posets Ultrametric](https://reader033.fdocuments.in/reader033/viewer/2022042417/5f32e8bcce0604000a3fd15f/html5/thumbnails/42.jpg)
Ramseyclasses
Miodrag Sokic
IntroductionMotivationTopologicaldynamicsModel theoryRamsey theoryThe KPT theory
QuestionsPosetsUltrametricspaces
ResultsPosetsUltrametric
IntroductionQuestionsResults
PosetsUltrametric spaces
Problems
UMF for Aut(US) isknown.
Aut(CUS) is extremelyamenable.
Ramsey degree forelements in US is known.
CU S is a Ramsey class.
OU S is not a Ramseyclass.
Calculate UMF forAut(OUS).
Calculate Ramsey degreesfor objects in OU S.
Miodrag Sokic Ramsey classes
![Page 43: Ramsey classes - math.wisc.edulempp/conf/asl12//Slides/Sokic.pdf · Introduction Motivation Topological dynamics Model theory Ramsey theory The KPT theory Questions Posets Ultrametric](https://reader033.fdocuments.in/reader033/viewer/2022042417/5f32e8bcce0604000a3fd15f/html5/thumbnails/43.jpg)
Ramseyclasses
Miodrag Sokic
IntroductionMotivationTopologicaldynamicsModel theoryRamsey theoryThe KPT theory
QuestionsPosetsUltrametricspaces
ResultsPosetsUltrametric
IntroductionQuestionsResults
PosetsUltrametric spaces
Problems
UMF for Aut(US) isknown.
Aut(CUS) is extremelyamenable.
Ramsey degree forelements in US is known.
CU S is a Ramsey class.
OU S is not a Ramseyclass.
Calculate UMF forAut(OUS).
Calculate Ramsey degreesfor objects in OU S.
Miodrag Sokic Ramsey classes
![Page 44: Ramsey classes - math.wisc.edulempp/conf/asl12//Slides/Sokic.pdf · Introduction Motivation Topological dynamics Model theory Ramsey theory The KPT theory Questions Posets Ultrametric](https://reader033.fdocuments.in/reader033/viewer/2022042417/5f32e8bcce0604000a3fd15f/html5/thumbnails/44.jpg)
Ramseyclasses
Miodrag Sokic
IntroductionMotivationTopologicaldynamicsModel theoryRamsey theoryThe KPT theory
QuestionsPosetsUltrametricspaces
ResultsPosetsUltrametric
IntroductionQuestionsResults
PosetsUltrametric spaces
Problems
UMF for Aut(US) isknown.
Aut(CUS) is extremelyamenable.
Ramsey degree forelements in US is known.
CU S is a Ramsey class.
OU S is not a Ramseyclass.
Calculate UMF forAut(OUS).
Calculate Ramsey degreesfor objects in OU S.
Miodrag Sokic Ramsey classes
![Page 45: Ramsey classes - math.wisc.edulempp/conf/asl12//Slides/Sokic.pdf · Introduction Motivation Topological dynamics Model theory Ramsey theory The KPT theory Questions Posets Ultrametric](https://reader033.fdocuments.in/reader033/viewer/2022042417/5f32e8bcce0604000a3fd15f/html5/thumbnails/45.jpg)
Ramseyclasses
Miodrag Sokic
IntroductionMotivationTopologicaldynamicsModel theoryRamsey theoryThe KPT theory
QuestionsPosetsUltrametricspaces
ResultsPosetsUltrametric
IntroductionQuestionsResults
PosetsUltrametric
Expansion
We consider posets with two linear orderings:
EOP = f(A,v,�,�) : (A,v,�) 2 OP & (A,v,�) 2 EPg.
Miodrag Sokic Ramsey classes
![Page 46: Ramsey classes - math.wisc.edulempp/conf/asl12//Slides/Sokic.pdf · Introduction Motivation Topological dynamics Model theory Ramsey theory The KPT theory Questions Posets Ultrametric](https://reader033.fdocuments.in/reader033/viewer/2022042417/5f32e8bcce0604000a3fd15f/html5/thumbnails/46.jpg)
Ramseyclasses
Miodrag Sokic
IntroductionMotivationTopologicaldynamicsModel theoryRamsey theoryThe KPT theory
QuestionsPosetsUltrametricspaces
ResultsPosetsUltrametric
IntroductionQuestionsResults
PosetsUltrametric
RP
Theorem
EOP is a Ramsey class which satis�es OP with respect to OP .
Corollary
tOP (A) = jle(v)j.
Corollary
UMF of Aut(OP) is a closed subset of the compact space ofall linear orderings LO � 2N�N.
Miodrag Sokic Ramsey classes
![Page 47: Ramsey classes - math.wisc.edulempp/conf/asl12//Slides/Sokic.pdf · Introduction Motivation Topological dynamics Model theory Ramsey theory The KPT theory Questions Posets Ultrametric](https://reader033.fdocuments.in/reader033/viewer/2022042417/5f32e8bcce0604000a3fd15f/html5/thumbnails/47.jpg)
Ramseyclasses
Miodrag Sokic
IntroductionMotivationTopologicaldynamicsModel theoryRamsey theoryThe KPT theory
QuestionsPosetsUltrametricspaces
ResultsPosetsUltrametric
IntroductionQuestionsResults
PosetsUltrametric
RP
Theorem
EOP is a Ramsey class which satis�es OP with respect to OP .
Corollary
tOP (A) = jle(v)j.
Corollary
UMF of Aut(OP) is a closed subset of the compact space ofall linear orderings LO � 2N�N.
Miodrag Sokic Ramsey classes
![Page 48: Ramsey classes - math.wisc.edulempp/conf/asl12//Slides/Sokic.pdf · Introduction Motivation Topological dynamics Model theory Ramsey theory The KPT theory Questions Posets Ultrametric](https://reader033.fdocuments.in/reader033/viewer/2022042417/5f32e8bcce0604000a3fd15f/html5/thumbnails/48.jpg)
Ramseyclasses
Miodrag Sokic
IntroductionMotivationTopologicaldynamicsModel theoryRamsey theoryThe KPT theory
QuestionsPosetsUltrametricspaces
ResultsPosetsUltrametric
IntroductionQuestionsResults
PosetsUltrametric
RP
Theorem
EOP is a Ramsey class which satis�es OP with respect to OP .
Corollary
tOP (A) = jle(v)j.
Corollary
UMF of Aut(OP) is a closed subset of the compact space ofall linear orderings LO � 2N�N.
Miodrag Sokic Ramsey classes
![Page 49: Ramsey classes - math.wisc.edulempp/conf/asl12//Slides/Sokic.pdf · Introduction Motivation Topological dynamics Model theory Ramsey theory The KPT theory Questions Posets Ultrametric](https://reader033.fdocuments.in/reader033/viewer/2022042417/5f32e8bcce0604000a3fd15f/html5/thumbnails/49.jpg)
Ramseyclasses
Miodrag Sokic
IntroductionMotivationTopologicaldynamicsModel theoryRamsey theoryThe KPT theory
QuestionsPosetsUltrametricspaces
ResultsPosetsUltrametric
IntroductionQuestionsResults
PosetsUltrametric
RP
Theorem
EOP is a Ramsey class which satis�es OP with respect to OP .
Corollary
tOP (A) = jle(v)j.
Corollary
UMF of Aut(OP) is a closed subset of the compact space ofall linear orderings LO � 2N�N.
Miodrag Sokic Ramsey classes
![Page 50: Ramsey classes - math.wisc.edulempp/conf/asl12//Slides/Sokic.pdf · Introduction Motivation Topological dynamics Model theory Ramsey theory The KPT theory Questions Posets Ultrametric](https://reader033.fdocuments.in/reader033/viewer/2022042417/5f32e8bcce0604000a3fd15f/html5/thumbnails/50.jpg)
Ramseyclasses
Miodrag Sokic
IntroductionMotivationTopologicaldynamicsModel theoryRamsey theoryThe KPT theory
QuestionsPosetsUltrametricspaces
ResultsPosetsUltrametric
IntroductionQuestionsResults
PosetsUltrametric
Expansions
Ultrametric spaces with two orderings:
COU S = f(X, d,�,� ) : (X, d,�) 2 OU S & (X, d,�) 2 CU Sg.
In the case that the set S � (0,+∞) has a minimumv = min(S), we consider the class:
COUminS = f(X, d,�,� ) 2COU S : (8x 2 X) �� Bv[x] =�� Bv[x]g.
Miodrag Sokic Ramsey classes
![Page 51: Ramsey classes - math.wisc.edulempp/conf/asl12//Slides/Sokic.pdf · Introduction Motivation Topological dynamics Model theory Ramsey theory The KPT theory Questions Posets Ultrametric](https://reader033.fdocuments.in/reader033/viewer/2022042417/5f32e8bcce0604000a3fd15f/html5/thumbnails/51.jpg)
Ramseyclasses
Miodrag Sokic
IntroductionMotivationTopologicaldynamicsModel theoryRamsey theoryThe KPT theory
QuestionsPosetsUltrametricspaces
ResultsPosetsUltrametric
IntroductionQuestionsResults
PosetsUltrametric
Expansions
Ultrametric spaces with two orderings:
COU S = f(X, d,�,� ) : (X, d,�) 2 OU S & (X, d,�) 2 CU Sg.
In the case that the set S � (0,+∞) has a minimumv = min(S), we consider the class:
COUminS = f(X, d,�,� ) 2COU S : (8x 2 X) �� Bv[x] =�� Bv[x]g.
Miodrag Sokic Ramsey classes
![Page 52: Ramsey classes - math.wisc.edulempp/conf/asl12//Slides/Sokic.pdf · Introduction Motivation Topological dynamics Model theory Ramsey theory The KPT theory Questions Posets Ultrametric](https://reader033.fdocuments.in/reader033/viewer/2022042417/5f32e8bcce0604000a3fd15f/html5/thumbnails/52.jpg)
Ramseyclasses
Miodrag Sokic
IntroductionMotivationTopologicaldynamicsModel theoryRamsey theoryThe KPT theory
QuestionsPosetsUltrametricspaces
ResultsPosetsUltrametric
IntroductionQuestionsResults
PosetsUltrametric
Expansions
Ultrametric spaces with two orderings:
COU S = f(X, d,�,� ) : (X, d,�) 2 OU S & (X, d,�) 2 CU Sg.
In the case that the set S � (0,+∞) has a minimumv = min(S), we consider the class:
COUminS = f(X, d,�,� ) 2COU S : (8x 2 X) �� Bv[x] =�� Bv[x]g.
Miodrag Sokic Ramsey classes
![Page 53: Ramsey classes - math.wisc.edulempp/conf/asl12//Slides/Sokic.pdf · Introduction Motivation Topological dynamics Model theory Ramsey theory The KPT theory Questions Posets Ultrametric](https://reader033.fdocuments.in/reader033/viewer/2022042417/5f32e8bcce0604000a3fd15f/html5/thumbnails/53.jpg)
Ramseyclasses
Miodrag Sokic
IntroductionMotivationTopologicaldynamicsModel theoryRamsey theoryThe KPT theory
QuestionsPosetsUltrametricspaces
ResultsPosetsUltrametric
IntroductionQuestionsResults
PosetsUltrametric
RP
Theorem
For non empty S � (0,+∞), COU S is a Ramsey class.
For non empty S � (0,+∞) where S has a minimum,COUmin
S is a Ramsey class.
Theorem
Let 0 /2 S � (0,+∞) be such that inf(S) /2 S. Then theclass COU S satis�es the ordering property with respect toOU S.
Let 0 /2 S � (0,+∞) be such that inf(S) 2 S. Then theclass COUmin
S satis�es the ordering property with respectto OU S.
Miodrag Sokic Ramsey classes
![Page 54: Ramsey classes - math.wisc.edulempp/conf/asl12//Slides/Sokic.pdf · Introduction Motivation Topological dynamics Model theory Ramsey theory The KPT theory Questions Posets Ultrametric](https://reader033.fdocuments.in/reader033/viewer/2022042417/5f32e8bcce0604000a3fd15f/html5/thumbnails/54.jpg)
Ramseyclasses
Miodrag Sokic
IntroductionMotivationTopologicaldynamicsModel theoryRamsey theoryThe KPT theory
QuestionsPosetsUltrametricspaces
ResultsPosetsUltrametric
IntroductionQuestionsResults
PosetsUltrametric
RP
Theorem
For non empty S � (0,+∞), COU S is a Ramsey class.
For non empty S � (0,+∞) where S has a minimum,COUmin
S is a Ramsey class.
Theorem
Let 0 /2 S � (0,+∞) be such that inf(S) /2 S. Then theclass COU S satis�es the ordering property with respect toOU S.
Let 0 /2 S � (0,+∞) be such that inf(S) 2 S. Then theclass COUmin
S satis�es the ordering property with respectto OU S.
Miodrag Sokic Ramsey classes
![Page 55: Ramsey classes - math.wisc.edulempp/conf/asl12//Slides/Sokic.pdf · Introduction Motivation Topological dynamics Model theory Ramsey theory The KPT theory Questions Posets Ultrametric](https://reader033.fdocuments.in/reader033/viewer/2022042417/5f32e8bcce0604000a3fd15f/html5/thumbnails/55.jpg)
Ramseyclasses
Miodrag Sokic
IntroductionMotivationTopologicaldynamicsModel theoryRamsey theoryThe KPT theory
QuestionsPosetsUltrametricspaces
ResultsPosetsUltrametric
IntroductionQuestionsResults
PosetsUltrametric
RP
Theorem
For non empty S � (0,+∞), COU S is a Ramsey class.
For non empty S � (0,+∞) where S has a minimum,COUmin
S is a Ramsey class.
Theorem
Let 0 /2 S � (0,+∞) be such that inf(S) /2 S. Then theclass COU S satis�es the ordering property with respect toOU S.
Let 0 /2 S � (0,+∞) be such that inf(S) 2 S. Then theclass COUmin
S satis�es the ordering property with respectto OU S.
Miodrag Sokic Ramsey classes
![Page 56: Ramsey classes - math.wisc.edulempp/conf/asl12//Slides/Sokic.pdf · Introduction Motivation Topological dynamics Model theory Ramsey theory The KPT theory Questions Posets Ultrametric](https://reader033.fdocuments.in/reader033/viewer/2022042417/5f32e8bcce0604000a3fd15f/html5/thumbnails/56.jpg)
Ramseyclasses
Miodrag Sokic
IntroductionMotivationTopologicaldynamicsModel theoryRamsey theoryThe KPT theory
QuestionsPosetsUltrametricspaces
ResultsPosetsUltrametric
IntroductionQuestionsResults
PosetsUltrametric
RP
Theorem
For non empty S � (0,+∞), COU S is a Ramsey class.
For non empty S � (0,+∞) where S has a minimum,COUmin
S is a Ramsey class.
Theorem
Let 0 /2 S � (0,+∞) be such that inf(S) /2 S. Then theclass COU S satis�es the ordering property with respect toOU S.
Let 0 /2 S � (0,+∞) be such that inf(S) 2 S. Then theclass COUmin
S satis�es the ordering property with respectto OU S.
Miodrag Sokic Ramsey classes
![Page 57: Ramsey classes - math.wisc.edulempp/conf/asl12//Slides/Sokic.pdf · Introduction Motivation Topological dynamics Model theory Ramsey theory The KPT theory Questions Posets Ultrametric](https://reader033.fdocuments.in/reader033/viewer/2022042417/5f32e8bcce0604000a3fd15f/html5/thumbnails/57.jpg)
Ramseyclasses
Miodrag Sokic
IntroductionMotivationTopologicaldynamicsModel theoryRamsey theoryThe KPT theory
QuestionsPosetsUltrametricspaces
ResultsPosetsUltrametric
IntroductionQuestionsResults
PosetsUltrametric
RP
Theorem
For non empty S � (0,+∞), COU S is a Ramsey class.
For non empty S � (0,+∞) where S has a minimum,COUmin
S is a Ramsey class.
Theorem
Let 0 /2 S � (0,+∞) be such that inf(S) /2 S. Then theclass COU S satis�es the ordering property with respect toOU S.
Let 0 /2 S � (0,+∞) be such that inf(S) 2 S. Then theclass COUmin
S satis�es the ordering property with respectto OU S.
Miodrag Sokic Ramsey classes
![Page 58: Ramsey classes - math.wisc.edulempp/conf/asl12//Slides/Sokic.pdf · Introduction Motivation Topological dynamics Model theory Ramsey theory The KPT theory Questions Posets Ultrametric](https://reader033.fdocuments.in/reader033/viewer/2022042417/5f32e8bcce0604000a3fd15f/html5/thumbnails/58.jpg)
Ramseyclasses
Miodrag Sokic
IntroductionMotivationTopologicaldynamicsModel theoryRamsey theoryThe KPT theory
QuestionsPosetsUltrametricspaces
ResultsPosetsUltrametric
IntroductionQuestionsResults
PosetsUltrametric
RP
Theorem
For non empty S � (0,+∞), COU S is a Ramsey class.
For non empty S � (0,+∞) where S has a minimum,COUmin
S is a Ramsey class.
Theorem
Let 0 /2 S � (0,+∞) be such that inf(S) /2 S. Then theclass COU S satis�es the ordering property with respect toOU S.
Let 0 /2 S � (0,+∞) be such that inf(S) 2 S. Then theclass COUmin
S satis�es the ordering property with respectto OU S.
Miodrag Sokic Ramsey classes
![Page 59: Ramsey classes - math.wisc.edulempp/conf/asl12//Slides/Sokic.pdf · Introduction Motivation Topological dynamics Model theory Ramsey theory The KPT theory Questions Posets Ultrametric](https://reader033.fdocuments.in/reader033/viewer/2022042417/5f32e8bcce0604000a3fd15f/html5/thumbnails/59.jpg)
Ramseyclasses
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IntroductionMotivationTopologicaldynamicsModel theoryRamsey theoryThe KPT theory
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RP
Theorem
For non empty S � (0,+∞), COU S is a Ramsey class.
For non empty S � (0,+∞) where S has a minimum,COUmin
S is a Ramsey class.
Theorem
Let 0 /2 S � (0,+∞) be such that inf(S) /2 S. Then theclass COU S satis�es the ordering property with respect toOU S.
Let 0 /2 S � (0,+∞) be such that inf(S) 2 S. Then theclass COUmin
S satis�es the ordering property with respectto OU S.
Miodrag Sokic Ramsey classes
![Page 60: Ramsey classes - math.wisc.edulempp/conf/asl12//Slides/Sokic.pdf · Introduction Motivation Topological dynamics Model theory Ramsey theory The KPT theory Questions Posets Ultrametric](https://reader033.fdocuments.in/reader033/viewer/2022042417/5f32e8bcce0604000a3fd15f/html5/thumbnails/60.jpg)
Ramseyclasses
Miodrag Sokic
IntroductionMotivationTopologicaldynamicsModel theoryRamsey theoryThe KPT theory
QuestionsPosetsUltrametricspaces
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PosetsUltrametric
Application
Theorem
Let S � (0,+∞) be non empty without a minimalelement. Then for A = (A, d,�)2OU S we have
tOUS(A) = jco((A, d))j.
Let S � (0,+∞) be non empty with a minimal element.Then for A 2OU S we have
tOUS(A) = jf�: (A, d,�,�) 2 COUminS gj.
Corollary
UMF of Aut(OUS) is closed subset of LO.
Miodrag Sokic Ramsey classes
![Page 61: Ramsey classes - math.wisc.edulempp/conf/asl12//Slides/Sokic.pdf · Introduction Motivation Topological dynamics Model theory Ramsey theory The KPT theory Questions Posets Ultrametric](https://reader033.fdocuments.in/reader033/viewer/2022042417/5f32e8bcce0604000a3fd15f/html5/thumbnails/61.jpg)
Ramseyclasses
Miodrag Sokic
IntroductionMotivationTopologicaldynamicsModel theoryRamsey theoryThe KPT theory
QuestionsPosetsUltrametricspaces
ResultsPosetsUltrametric
IntroductionQuestionsResults
PosetsUltrametric
Application
Theorem
Let S � (0,+∞) be non empty without a minimalelement. Then for A = (A, d,�)2OU S we have
tOUS(A) = jco((A, d))j.
Let S � (0,+∞) be non empty with a minimal element.Then for A 2OU S we have
tOUS(A) = jf�: (A, d,�,�) 2 COUminS gj.
Corollary
UMF of Aut(OUS) is closed subset of LO.
Miodrag Sokic Ramsey classes
![Page 62: Ramsey classes - math.wisc.edulempp/conf/asl12//Slides/Sokic.pdf · Introduction Motivation Topological dynamics Model theory Ramsey theory The KPT theory Questions Posets Ultrametric](https://reader033.fdocuments.in/reader033/viewer/2022042417/5f32e8bcce0604000a3fd15f/html5/thumbnails/62.jpg)
Ramseyclasses
Miodrag Sokic
IntroductionMotivationTopologicaldynamicsModel theoryRamsey theoryThe KPT theory
QuestionsPosetsUltrametricspaces
ResultsPosetsUltrametric
IntroductionQuestionsResults
PosetsUltrametric
Application
Theorem
Let S � (0,+∞) be non empty without a minimalelement. Then for A = (A, d,�)2OU S we have
tOUS(A) = jco((A, d))j.
Let S � (0,+∞) be non empty with a minimal element.Then for A 2OU S we have
tOUS(A) = jf�: (A, d,�,�) 2 COUminS gj.
Corollary
UMF of Aut(OUS) is closed subset of LO.
Miodrag Sokic Ramsey classes
![Page 63: Ramsey classes - math.wisc.edulempp/conf/asl12//Slides/Sokic.pdf · Introduction Motivation Topological dynamics Model theory Ramsey theory The KPT theory Questions Posets Ultrametric](https://reader033.fdocuments.in/reader033/viewer/2022042417/5f32e8bcce0604000a3fd15f/html5/thumbnails/63.jpg)
Ramseyclasses
Miodrag Sokic
IntroductionMotivationTopologicaldynamicsModel theoryRamsey theoryThe KPT theory
QuestionsPosetsUltrametricspaces
ResultsPosetsUltrametric
IntroductionQuestionsResults
PosetsUltrametric
Application
Theorem
Let S � (0,+∞) be non empty without a minimalelement. Then for A = (A, d,�)2OU S we have
tOUS(A) = jco((A, d))j.
Let S � (0,+∞) be non empty with a minimal element.Then for A 2OU S we have
tOUS(A) = jf�: (A, d,�,�) 2 COUminS gj.
Corollary
UMF of Aut(OUS) is closed subset of LO.
Miodrag Sokic Ramsey classes
![Page 64: Ramsey classes - math.wisc.edulempp/conf/asl12//Slides/Sokic.pdf · Introduction Motivation Topological dynamics Model theory Ramsey theory The KPT theory Questions Posets Ultrametric](https://reader033.fdocuments.in/reader033/viewer/2022042417/5f32e8bcce0604000a3fd15f/html5/thumbnails/64.jpg)
Ramseyclasses
Miodrag Sokic
IntroductionMotivationTopologicaldynamicsModel theoryRamsey theoryThe KPT theory
QuestionsPosetsUltrametricspaces
ResultsPosetsUltrametric
IntroductionQuestionsResults
PosetsUltrametric
Application
Theorem
Let S � (0,+∞) be non empty without a minimalelement. Then for A = (A, d,�)2OU S we have
tOUS(A) = jco((A, d))j.
Let S � (0,+∞) be non empty with a minimal element.Then for A 2OU S we have
tOUS(A) = jf�: (A, d,�,�) 2 COUminS gj.
Corollary
UMF of Aut(OUS) is closed subset of LO.
Miodrag Sokic Ramsey classes
![Page 65: Ramsey classes - math.wisc.edulempp/conf/asl12//Slides/Sokic.pdf · Introduction Motivation Topological dynamics Model theory Ramsey theory The KPT theory Questions Posets Ultrametric](https://reader033.fdocuments.in/reader033/viewer/2022042417/5f32e8bcce0604000a3fd15f/html5/thumbnails/65.jpg)
Ramseyclasses
Miodrag Sokic
IntroductionMotivationTopologicaldynamicsModel theoryRamsey theoryThe KPT theory
QuestionsPosetsUltrametricspaces
ResultsPosetsUltrametric
IntroductionQuestionsResults
PosetsUltrametric
Thank you
Miodrag Sokic Ramsey classes