Constructive Semantics for Description Logics · Constructive Semantics for Description Logics ASP...

Constructive Semantics for Description LogicsASP Based Generation of Information Terms for

Constructive EL

Loris Bozzato

DKM - Data and Knowledge Management Research Unit,FBK - Fondazione Bruno Kessler, Trento, Italy

UniVR Logic Seminar

February 2, 2017 – Verona, Italy

L. Bozzato (DKM - FBK) Constructive Semantics for DLs 02/02/2017 1 / 54

Description logics

Description logics (DL)A family of logic based Knowledge Representation formalisms

Main features:Expressive but decidable fragments of FOLFormally defined semantics⇒ ReasoningEfficient implementations for key problemsRelevant applications (Semantic Web)

Elements:Concepts: classes of objects HumanRoles: binary relations between objects hasChild

Complex descriptions:Concept constructors (u, t, ¬) Squaret ¬RoundRole restrictions (∃, ∀, >) > 2hasChild

∀hasBrother.( ∃isChildOf.Father )

Description logics

Constructive logics

Constructive logicsFormalizations of ideas from constructivism

Brouwer-Heyting-Kolmogorov (BHK) or proof interpretationSemiformal presentation of a constructive semanticsE.g. propositional part:

A proof of A∧ B is composed from proofs of A and BA proof of A∨ B is composed of a proof for A or BA proof of A→B is construction transforming proofs of A in proofs for B⊥ is an unprovable formula (thus A→⊥ = ¬A)

Possible formalizations:IntuitionismRecursive realizabilityInformation terms semantics

Constructive logics

Constructive logicsFormalizations of ideas from constructivism

Brouwer-Heyting-Kolmogorov (BHK) or proof interpretationSemiformal presentation of a constructive semanticsE.g. propositional part:

A proof of A∧ B is composed from proofs of A and BA proof of A∨ B is composed of a proof for A or BA proof of A→B is construction transforming proofs of A in proofs for B⊥ is an unprovable formula (thus A→⊥ = ¬A)

Possible formalizations:IntuitionismRecursive realizabilityInformation terms semantics

Constructive logics

Characteristic properties:Disjunction property (DP):“Whenever it proves a disjunction formula,it proves one of the disjoints”Explicit definability property (ED):“Whenever it proves an existential formula,it presents a witness of the existence”

Constructivism and Computer Science:Formulas-as-types (Curry-Howard isomorphism)Proofs-as-programs

Constructive description logics

Constructive description logicsConstructive interpretations of description logics

MotivationsComputational interpretation of proofs and formulasUseful in domains with dynamic and incomplete knowledge

Proposals

[de Paiva, 2005]: translations of DLs in constructive systems

[Kaneiwa, 2005]: definitions for different constructive negations in DLs

[Odintsov and Wansing, 2003]: inconsistency tolerant version of DLs

[Mendler and Scheele, 2010]: Kripke semantics with “fallible” elements

BCDL [Ferrari et al., 2010]: Information terms semantics + natural deduction

KALC [Bozzato, 2011]: Kripke-style semantics + tableaux algorithm

Constructive DLs and applications

Constructive DLs mostly studied from formal point of view...Limited proposals for application in KR and Semantic Web languages

Applications (examples)

[Mendler and Scheele, 2009]: reasoning over incomplete data streams[Haeusler et al., 2011]: conflict management on legal ontologies[Hilia et al., 2012]: semantic services compositions (on BCDL)

Idea: ...let’s try to bridge the gap!

ProposalTheory: study relations between IT and ASPPractice: prototype over “off the shelf” tools (OWL API, dlv)

ContributionsELc: IT semantics for description logic ELASP and IT semantics: formal relation and datalog rewritingAsp-it prototype: ASP based IT generator for OWL-EL ontologies

Overview

1 Constructive semantics for DLs

2 ELc: constructive semantics for EL

3 Answer sets and IT semantics

4 ASP based generation of IT

5 Asp-it prototype

Overview

5 Asp-it prototype

Proposals

Known proposals[de Paiva, 2005]: translations of DLs in constructive systems[Kaneiwa, 2005]: definitions for different constructive negations in DLs[Odintsov and Wansing, 2003]: inconsistency tolerant version of DLs[Mendler and Scheele, 2010]: Kripke semantics with “fallible” elements

BCDL [Ferrari et al., 2010]: Information terms semantics + ND calculusKALC [Bozzato, 2011]: Kripke-style semantics + tableaux algorithm

Proposal [de Paiva, 2005]

MotivationExtend proof-theoretical results (Curry-Howard) on DLsDefine a context-sensitive DL

Proposals3 different interpretations of ALC in constructive systems:

IALC: from ALC to IFOL (via ALC → FOL translation)

iALC: from ALC to IK (via ALC → Km translation)

cALC: from ALC to CK (via ALC → Km translation)

Proposal [Kaneiwa, 2005]

MotivationRepresentation of different notions of negative information in DLs(contraries, contradictories and subcontraries)E.g. difference between Happy, Unhappy,¬Happy,¬Unhappy

Proposals2 different extensions to ALC semantics(different interactions between constructive and classical negation)

tableaux algorithm for satisfiability

Similar works: [Kamide, 2010a, Kamide, 2010b]

Paraconsistent and temporal versions of ALC, based on a similarsemantics

Proposal [Odintsov and Wansing, 2003]

IdeasParaconsistent versions of ALCConstructive semantics to represent partial information

Proposal [Odintsov and Wansing, 2003]

3 constructive paraconsistent semantics for ALC(Different translations to four valued logic N4)

complete tableaux calculus for each logic

Further work [Odintsov and Wansing, 2008]

Reviews of calculi, tableaux procedure for one of the presented logics

Proposal [Mendler and Scheele, 2010]

IdeaRepresentation of partial knowledge and consistency under abstraction

Evolving OWA: stages of information with changing properties andabstract individuals

ProposalcALC: Kripke semantics for ALC with fallible entities

fallible entities ⊥I : contradictory domain elements(maximal poset elements or undefined role fillers)

complete and decidable Hilbert and tableaux calculi

Application [Mendler and Scheele, 2009]

Reasoning on data streams in auditing domain

Our proposals

BCDL [Bozzato et al., 2007, Bozzato et al., 2009b, Ferrari et al., 2010]

Information terms semantics + natural deduction calculusÔ computational interpretation of proofs (Proofs as programs)

KALC∞ [Bozzato et al., 2009a, Villa, 2010]

Kripke-style semantics + tableaux calculusÔ possibly infinite models, efficient treatment of implications

KALC [Bozzato et al., 2010, Bozzato, 2011]

Kripke-style semantics + tableaux algorithmÔ finite models, decidability from terminating tableau procedure

BCDL: information terms semantics for ALC

BCDL: Basic Constructive Description Logic [Ferrari et al., 2010]

Information terms semantics for ALCNatural deduction calculus NDc

Information terms (IT) [Miglioli et al., 1989]

Syntactic objects justifying validity of formulas in classical modelsrealization of BHK interpretationrelated to realizability interpretations

BCDL: information terms semantics for ALC

Information terms (IT) justificationE.g.: Truth of ∃R.C(a) inM justified by IT (b, α) s.t.

M |= R(a, b) andα justifies truth of C(b)

Features:Classical reading of DL formulasSimple proof theoretical characterization by NDc

Computational interpretation of proofsNatural notion of state

ALCG syntax and classical semantics

Syntax is the same as ALC, adding a set of generators NG

ConceptsC ::= A | G | ¬C | Cu C | Ct C | ∃R.C | ∀R.C

FormulasK ::= ⊥ | R(t, s) | C(t) | ∀GC

where A ∈ NC, R ∈ NR, t, s ∈ NI and G ∈ NG

Generators NGConcepts over fixed set of individual names dom(G) = {c1, . . . , cn}Ô limited form of subsumption: ∀GC ≡ G v C

ALCG syntax and classical semantics

Validity of formulas: given a modelM = (∆M, ·M)

M 6|= ⊥

M |= R(t, s) iff (tM, sM) ∈ RM

M |= H(t) iff tM ∈ HM

M |= ∀GH iff GM = {cM1 , . . . , cMn } ⊆ HM

BCDL information terms semantics

Information terms ITN (K)Structured objects that constructively justify the truth of a formula K

ITN (K) = {tt}, if K is atomicITN (C1 t C2(c)) = {(k, α) | k ∈ {1, 2} and α∈ IT(Ck(c))}

RealizabilityMB 〈α〉KTruth of K in a modelM justified w.r.t. α

MB 〈tt〉K iffM |= KMB 〈(k, α)〉C1 t C2(c) iffMB 〈α〉 Ck(c)

Theorem (classical and IT semantics)M |= K iff there exists α ∈ IT(K) such thatMB 〈α〉K

ITN (K) = {tt} for K atomic or negated MB 〈tt〉K iffM |= K

ITN (C1 u C2(c))= IT(C1(c))× IT(C2(c)) MB 〈(α, β)〉C1 u C2(c) iffMB 〈α〉C1(c)andMB 〈β〉C2(c)

ITN (C1 t C2(c))= IT(C1(c)) ] IT(C2(c)) MB 〈(k, α)〉C1 t C2(c) iffMB 〈α〉Ck(c)

ITN (∃R.C(c))= N ×⋃d∈N IT(C(d)) MB 〈(d, α)〉 ∃R.C(c) iffM |= R(c, d)

andMB 〈α〉C(d)

ITN (∀R.C(c))= (⋃

d∈N IT(C(d)))N MB 〈φ〉 ∀R.C(c) iffM |= ∀R.C(c) and,for every d ∈ N , if M |= R(c, d) thenMB 〈φ(d)〉C(d)

ITN (∀GC)= (⋃

d∈dom(G) IT(C(d)))dom(G) MB 〈φ〉 ∀GC iff, for every d ∈ dom(G),MB 〈φ(d)〉C(d)

Natural deduction calculus ND

Calculus ND : natural deduction calculus for ALCG

Γ··· π′

Ak(t)tIk

A1 tA2(t)

Γ1··· π1

∃R.A(t)

Γ2, [R(t, p), A(p)]··· π2

Γ′··· π′

G(t)∀GE

Γ, [¬H(t)]··· π′

⊥¬E

TheoremND is sound and complete w.r.t. ALCG

leaving aside generators rules, ND is sound and complete w.r.t. ALC

Natural deduction calculus NDc

Calculus NDc: natural deduction calculus for BCDL

Every rule fromND

(minus ¬E)

Γ··· π′

¬¬C(t)At

Γ··· π′

∀R.¬¬H(t)KUR

¬¬∀R.H(t)

NoteKUR corresponds to the Kuroda axiom schema Kur

Kur ≡ ∀x.¬¬A(x) → ¬¬∀x.A(x)

Soundness of NDc

Operator ΦπN : Given a proof π : Γ ` K over N :

ΦπN : ITN (Γ)→ ITN (K)

Note: computable function, inductively defined on depth of π

Example: tIk

If last rule in π is tIk with k ∈ {1, 2}, then:

ΦπN : ITN (Γ)→ ITN (C1 t C2(t))

defined as:

ΦπN (γ) = ( k, Φπ′

N (γ) )

tIk ruleΓ··· π′

Ak(t)tIk

A1 tA2(t)

Soundness of NDc: computational interpretation

Theorem (Soundness)If π : Γ ` K, then:

Γ |= K.IfMB 〈γ〉 Γ thenMB 〈Φπ

N (γ)〉K. (constructive consequence)

Computational interpretationGiven a proof π of a formula K. . .. . . its Φπ

N provides a “program” to compute an IT for K

Properties of NDc

Theorem (Completeness)Γ | BCDL K iff K is a constructive consequence of Γ.

Constructive propertiesFor Γ of Harrop formulas (no t and ∃):

Disjunction property (DP):If Γ | BCDL At B(c), then Γ | BCDL A(c) or Γ | BCDL B(c).

Explicit definability property (EDP):If Γ | BCDL ∃R.A(c), then there exists d ∈ NI such thatΓ | BCDL R(c, d) and Γ | BCDL A(d).

Overview

5 Asp-it prototype

Overview

5 Asp-it prototype

ELc: information terms semantics for EL [Baader, 2003]

Simple restriction of BCDL to EL

Why EL?The most simple DL s.t. semantics withconstructive properties (ED) can be definedWell-known and used DL language, base of OWL EL profile

DL language L

Syntax is the same as EL, adding a set of generators NG

ConceptsC ::= A | G | Cu C | ∃R.C

FormulasK ::= R(s, t) | C(t) | ∀GC

Generators NGConcepts over fixed set of individual names DOM(G) = {c1, . . . , cn}Ô limited form of subsumption: ∀GC ≡ G v C

> operator: special generator >N s.t. DOM(>N ) = N

DL language L

Syntax is the same as EL, adding a set of generators NG

ConceptsC ::= A | G | Cu C | ∃R.C

FormulasK ::= R(s, t) | C(t) | ∀GC

Generators NGConcepts over fixed set of individual names DOM(G) = {c1, . . . , cn}Ô limited form of subsumption: ∀GC ≡ G v C

> operator: special generator >N s.t. DOM(>N ) = N

EL: classical semantics

Classical model: M = (∆M, ·M)

Individuals: cM ∈ ∆M

Atomic concepts: AM ⊆ ∆M

Roles: RM ⊆ ∆M × ∆M

Generators: GM = {cM1 , . . . , cMn }

Non-atomic concepts:

(CuD)M = CM ∩DM

(∃R.C)M = { c ∈ ∆M | there is d s.t. (c, d) ∈ RM and d ∈ CM }

Validity of formulas:

M |= R(s, t) iff (sM, tM) ∈ RM

M |= C(t) iff tM ∈ CM

M |= ∀GC iff GM ⊆ CM

Example: Food and Wines

Scenario: food and wines knowledge base [Brachman et al., 1991]

Task: pair each food with the correct wine

Conditions:Pairings:

Meat with red winesFish with white wines

For every food, a correct wine colorFor every wine color, at least one wine

Example: Food and Wines KB

Knowledge base KW:

TBox T :

(Ax1) : ∀Food∃goesWith.Color ≡ Food v ∃goesWith.Color

(Ax2) : ∀Color∃isColorOf.Wine ≡ Color v ∃isColorOf.Wine

DOM(Food) = {fish,meat} DOM(Color) = {red,white}

ABox A:

Wine(barolo)

Wine(chardonnay)

isColorOf(red,barolo)

isColorOf(white,chardonnay)

goesWith(fish,white)

goesWith(meat,red)

Example: Food and Wines KB

Knowledge base KW:

TBox T :

DOM(Food) = {fish,meat} DOM(Color) = {red,white}

ABox A:

Wine(barolo)

Wine(chardonnay)

isColorOf(red,barolo)

isColorOf(white,chardonnay)

goesWith(fish,white)

goesWith(meat,red)

ELc: information terms semantics

Given N ⊆ NI finite and a closed formula K ∈ LN

Information terms ITN (K)ITN (K) = {tt}, if K is atomic

ITN (C1 u C2(c)) = {(α, β) | α∈ IT(C1(c)) and β∈ IT(C2(c))}ITN (∃R.C(c)) = {(d, α) | d ∈ N and α∈ IT(C(d))}ITN (∀GC) = { φ : DOM(G)→ ⋃

d∈dom(G) ITN (C(d)) | φ(d) ∈ ITN (C(d)) }

RealizabilityMB 〈α〉KMB 〈tt〉K iffM |= K

MB 〈(α, β)〉C1 u C2(c) iffMB 〈α〉C1(c) andMB 〈β〉C2(c)

MB 〈(d, α)〉 ∃R.C(c) iffM |= R(c, d) andMB 〈α〉C(d)

MB 〈φ〉 ∀GC iff, for every d ∈ DOM(G),MB 〈φ(d)〉C(d)

ITN (C1 u C2(c)) = {(α, β) | α∈ IT(C1(c)) and β∈ IT(C2(c))}

ITN (∃R.C(c)) = {(d, α) | d ∈ N and α∈ IT(C(d))}ITN (∀GC) = { φ : DOM(G)→ ⋃

ITN (C1 u C2(c)) = {(α, β) | α∈ IT(C1(c)) and β∈ IT(C2(c))}ITN (∃R.C(c)) = {(d, α) | d ∈ N and α∈ IT(C(d))}

ITN (∀GC) = { φ : DOM(G)→ ⋃d∈dom(G) ITN (C(d)) | φ(d) ∈ ITN (C(d)) }

ITN (C1 u C2(c)) = {(α, β) | α∈ IT(C1(c)) and β∈ IT(C2(c))}ITN (∃R.C(c)) = {(d, α) | d ∈ N and α∈ IT(C(d))}ITN (∀GC) = { φ : DOM(G)→ ⋃

Example: IT for Food and Wines

(Ax1) :

∀Food∃goesWith.Color ≡ Food v ∃goesWith.Color

φ1 ∈ ITN (Ax1) :

[ fish 7→ (white,tt), meat 7→ (red,tt) ]

Example: IT for Food and Wines

(Ax2) :

∀Color∃isColorOf.Wine ≡ Color v ∃isColorOf.Wine

φ2 ∈ ITN (Ax2) :

[ red 7→ (barolo,tt), white 7→ (chardonnay,tt) ]

LetM be a model of KW: then,MB 〈(φ1, φ2)〉 T

Constructive consequence

Theorem (classical and IT semantics)If α ∈ IT(K),MB 〈α〉K impliesM |= K

Constructive consequence Γ|=c K:Γ|=c K iffMB 〈γ〉 Γ impliesMB 〈η〉K

Computational interpretation

Γ|=c K implicitly defines a semantic map ΦN such that:

ifMB 〈γ〉 Γ thenMB 〈ΦN (γ)〉K

In BCDL we can extract ΦN from natural deduction proofs[Bozzato et al., 2007, Ferrari et al., 2010]

Constructive consequence

Theorem (classical and IT semantics)If α ∈ IT(K),MB 〈α〉K impliesM |= K

Constructive consequence Γ|=c K:Γ|=c K iffMB 〈γ〉 Γ impliesMB 〈η〉K

Computational interpretation

Γ|=c K implicitly defines a semantic map ΦN such that:

ifMB 〈γ〉 Γ thenMB 〈ΦN (γ)〉K

In BCDL we can extract ΦN from natural deduction proofs[Bozzato et al., 2007, Ferrari et al., 2010]

Overview

5 Asp-it prototype

Overview

5 Asp-it prototype

Answer sets for formulas and information terms

TaskCompute information terms of input KB Γ in EL

IdeaUse relations across IT and Answer Sets semantics[Fiorentini and Ornaghi, 2007] on propositional nested expressions

Ô We extend these results to ELc formulas

Answer set

lp-interpretationSet of closed atomic formulas in LN

Given a closed K ∈ LN :

I |= K, iff K ∈ I and K is atomicI |= CuD(c) iff I |= C(c) and I |= D(c)I |= ∃R.C(c) iff R(c, d) ∈ I for d ∈ N and I |= C(d)

I |= ∀GC iff for every e ∈ DOM(G), I |= C(e)I |= Γ iff I |= K for K ∈ Γ

Answer setI answer set for set of closed formulas Γ ⊆ LN iff:

I |= Γfor every I′ ⊆ I, I′ |= Γ implies I′ = I (minimality)

Answer set

lp-interpretationSet of closed atomic formulas in LN

Given a closed K ∈ LN :

I |= K, iff K ∈ I and K is atomicI |= CuD(c) iff I |= C(c) and I |= D(c)I |= ∃R.C(c) iff R(c, d) ∈ I for d ∈ N and I |= C(d)

I |= ∀GC iff for every e ∈ DOM(G), I |= C(e)I |= Γ iff I |= K for K ∈ Γ

Answer setI answer set for set of closed formulas Γ ⊆ LN iff:

I |= Γfor every I′ ⊆ I, I′ |= Γ implies I′ = I (minimality)

Answers of pieces of information

Piece of information (POI)〈η〉K with closed K ∈ LN and η ∈ ITN (K)(Idea: “state” of K defined by η)

Answers ans(〈η〉K)Set of closed atomic formulas: (Idea: “information content” of 〈η〉K)

ans(〈tt〉K) = {K}, with K atomic

ans(〈(α, β)〉A1 uA2(c)) = ans(〈α〉A1(c)) ∪ ans(〈β〉A2(c))

ans(〈(d, α)〉∃R.A(c)) = {R(c, d)} ∪ ans(〈α〉A(d))

ans(〈φ〉∀GA) =⋃

d∈DOM(G) ans(〈φ(d)〉A(d))

Minimal POI〈η〉K is minimal iff @µ with ans(〈µ〉K) ⊂ ans(〈η〉K)

Example: answers of POIs

φ1 ∈ ITN (Ax1) : [ fish 7→ (white,tt), meat 7→ (red,tt) ]

ans(〈φ1〉Ax1) = {Color(white), goesWith(fish,white),Color(red), goesWith(meat,red)}

φ2 ∈ ITN (Ax2) : [ red 7→ (barolo,tt), white 7→ (chardonnay,tt) ]

ans(〈φ2〉Ax2) = {Wine(barolo), isColorOf(red,barolo),Wine(chardonnay),isColorOf(white,chardonnay)}

Example: answers of POIs

φ1 ∈ ITN (Ax1) : [ fish 7→ (white,tt), meat 7→ (red,tt) ]

ans(〈φ1〉Ax1) = {Color(white), goesWith(fish,white),Color(red), goesWith(meat,red)}

φ2 ∈ ITN (Ax2) : [ red 7→ (barolo,tt), white 7→ (chardonnay,tt) ]

ans(〈φ2〉Ax2) = {Wine(barolo), isColorOf(red,barolo),Wine(chardonnay),isColorOf(white,chardonnay)}

Result: answer sets and minimal POI

TheoremFor every modelM,MB 〈η〉K iffM |= ans(〈η〉K)

TheoremI answer set for K iff∃ a minimal 〈η〉K such that I = ans(〈η〉K)

Overview

5 Asp-it prototype

Overview

5 Asp-it prototype

ASP based generation of information terms

Solution to generate (minimal) IT:1 Compute answer sets of input KB Γ2 For each formula K ∈ Γ, use recursive definition of ans(〈η〉K) to

reconstruct IT η

Idea: computation of answer setsTranslate input KB to datalog program

Ô Translation includes rules recursively constructing ITs(generate-and-test approach)

Model generating rewriting

Model generating rewriting (P1)Generates interpretations for input EL formulas:

A(b) 7→ { is(b, A)← is(b, lA). }R(a, b) 7→ { rel(a, R, b). }

CuD(a) 7→ { is(a, lC)← is(a, lCuD).is(a, lD)← is(a, lCuD). } ∪ P1(C(a)) ∪ P1(D(a))

∃R.C(a) 7→ { is(x, lC)← rel(a, R, x), is(a, l∃R.C). } ∪ P1(C(x))

∀GC 7→ { is(x, lC)← is(x, G). } ∪ P1(C(x))

NotesFixed set R of roles assertions from input KBLabelling for complex concepts lCAtomic assertions and generator domains added as facts

IT generating rewriting

IT generating rewriting (P2)Retrieves IT as complex terms, using definition of ans(〈η〉K):

A(b) 7→ { is_it(tt, b, lA)← is(b, A). }R(a, b) 7→ { rel_it(tt, a, R, b)← rel(a, R, b). }

CuD(a) 7→ { is_it([x, y], a, lCuD)←is_it(x, a, lC), is_it(y, a, lD). } ∪ P2(C(a)) ∪ P2(D(a))

∃R.C(a) 7→ { is_it([x, y], a, l∃R.C)←rel_it(tt, a, R, x), is_it(y, x, lC). } ∪ P2(C(x))

∀GC 7→ { isa_it([x, y], G, lC)← is(x, G), is_it(y, x, lC). } ∪ P2(C(x))

Complete rewriting (P)P(Γ) = P1(Γ) ∪ P2(Γ)

Correctness

Let IT(K, I) be the set of IT “returned” by P2 for formula K andinterpretation I for P(Γ)

TheoremLet I be the (unique) answer set for P(Γ).If η ∈ IT(K, I), then ∃ lp-interpretation I′ for Γ s.t. ans(〈η〉K) ⊆ I′

Example

Suppose we add:

Wine(teroldego) isColorOf(red,teroldego)

Applying P2(Ax2) to the model computed by P1(KW):

[red, [barolo,tt]], [red, [teroldego,tt]], [white, [chardonnay,tt]]

(Ax3) : ∀Food∃goesWith.(Coloru ∃isColorOf.Wine)

Applying P2(Ax3):

[fish, [white, [tt, [chardonnay,tt]]]],

[meat, [red, [tt, [barolo,tt]]]],

[meat, [red, [tt, [teroldego,tt]]]]

Example

Suppose we add:

Wine(teroldego) isColorOf(red,teroldego)

Applying P2(Ax2) to the model computed by P1(KW):

[red, [barolo,tt]], [red, [teroldego,tt]], [white, [chardonnay,tt]]

(Ax3) : ∀Food∃goesWith.(Coloru ∃isColorOf.Wine)

Applying P2(Ax3):

[fish, [white, [tt, [chardonnay,tt]]]],

[meat, [red, [tt, [barolo,tt]]]],

[meat, [red, [tt, [teroldego,tt]]]]

Overview

5 Asp-it prototype

Overview

5 Asp-it prototype

Asp-it prototype

Asp-itJava-based command line application:

Input: OWL-EL ontology ΓOutput: ontology Γ′ annotated with IT (elc:hasIT)

ToolsOWL API: ontology I/O, axioms annotationDLV: models computation (via DLVWrapper)

IT generation process

DLV system

Output

ontology

Rewrite

Annotate

Datalog

rewriting

Retrieve

Info.Terms

Prototype and examples available at:https://github.com/dkmfbk/asp-it

Conclusions

Summary:ELc: IT semantics for description logic ELASP and IT semantics: formal relation and datalog rewritingAsp-it prototype: ASP based IT generator for OWL-EL ontologies

Future works:Integrate procedures for transformation of IT(Calculus and proofs-as-programs)

Applications: synthesis of SemanticServices [Bozzato and Ferrari, 2010a]

Extend to larger DLs: SROEL (full OWL EL), ALC (BCDL)

App. directions: IT and states

IT and statesInformation terms encode a natural notion of stateUsed in [Ferrari et al., 2008] to represent system snapshots

Ô Action formalism for ALC [Bozzato et al., 2009b]

An action formalism based on IT semantics of BCDL

System description and statesTheory T: description of a system

TBox: system constraints (general properties)ABox: current state of the system

State: α ∈ IT(T)State consistency: if there is a modelM s.t. MB 〈α〉T

App. directions: IT and states

IT and statesInformation terms encode a natural notion of stateUsed in [Ferrari et al., 2008] to represent system snapshots

Ô Action formalism for ALC [Bozzato et al., 2009b]

An action formalism based on IT semantics of BCDL

System description and statesTheory T: description of a system

TBox: system constraints (general properties)ABox: current state of the system

State: α ∈ IT(T)State consistency: if there is a modelM s.t. MB 〈α〉T

App. directions: action language

Action: P ⇒ QInformal reading

If the preconditions P hold in a state α, the action can be applied

In the resulting state the postconditions Q must hold

Information content IC(〈α〉T):minimal set of atomic formulas encoding info. from 〈α〉T

Applicability: an action is active if P ⊆ IC(〈α〉T)

Action output Out(α): update IC(〈α〉T) with Q

GENITAlgorithm to build up a state (IT) for a system, given an action outputIt can be used to trace reasons for inconsistency

App. directions: web services composition

Service composition in BCDL [Bozzato and Ferrari, 2010b]

Calculus for definition of Semantic Web Services compositionsRelated to program synthesis in constr. logics [Miglioli et al., 1986]

Services as combined functions "computing" information terms

Composition calculus SC

s(x) :: P⇒ Q

Π1 : s1(x) :: P1 ⇒ Q1· · ·

Πn : sn(x) :: Pn ⇒ Qn

Applicability conditions (AC):constraints for correctness of rule application

Computational interpretation (CI):computational reading of logical rule

ResultIf a composition meets the ACs of its rules, then its computationalinterpretation is sound

s(x) :: P⇒ Q

Π1 : s1(x) :: P1 ⇒ Q1· · ·

s(x) :: P⇒ Q

Π1 : s1(x) :: P1 ⇒ Q1· · ·

Thank you for listening

Constructive Semantics for Description LogicsASP Based Generation of Information Terms for Constructive EL

Loris Bozzatobozzato@fbk.eu

https://dkm.fbk.eu/

DKM - Data and Knowledge Management Research Unit,FBK - Fondazione Bruno Kessler, Trento, Italy

References I

Baader, F. (2003).Terminological cycles in a description logic with existential restrictions.In IJCAI-03, pages 325–330. Morgan Kaufmann.

Bozzato, L. (2011).Kripke semantics and tableau procedures for constructive description logics.PhD thesis, DICOM – Università degli Studi dell’Insubria.

Bozzato, L. and Ferrari, M. (2010a).Composition of semantic web services in a constructive description logic.In RR2010, volume 6333 of Lecture Notes in Computer Science, pages 223–226. Springer.

Bozzato, L. and Ferrari, M. (2010b).Composition of Semantic Web Services in a Constructive Description Logic.In Proceedings of the 4th International Conference on Web Reasoning and Rule Systems (RR2010), volume 6333 ofLecture Notes in Computer Science, pages 223–226. Springer.

Bozzato, L., Ferrari, M., Fiorentini, C., and Fiorino, G. (2007).A constructive semantics for ALC.In DL2007, volume 250 of CEUR-WP, pages 219–226. CEUR-WS.org.

Bozzato, L., Ferrari, M., Fiorentini, C., and Fiorino, G. (2010).A decidable constructive description logic.In Proceedings of the 12th European Conference on Logics in Artificial Intelligence (JELIA 2010), Lecture Notes inComputer Science. Springer.

Bozzato, L., Ferrari, M., and Villa, P. (2009a).A note on constructive semantics for description logics.In CILC09 - 24-esimo Convegno Italiano di Logica Computazionale.

References II

Bozzato, L., Ferrari, M., and Villa, P. (2009b).Actions Over a Constructive Semantics for Description Logics.Fundamenta Informaticae, 96(3):253–269.

Brachman, R., McGuinness, D., Patel-Schneider, P., Resnick, L., and Borgida, A. (1991).Living with CLASSIC: When and how to use a KL-ONE-like language.In Principles of Semantic Networks, pages 401–456. Morgan Kauffman.

de Paiva, V. (2005).Constructive description logics: what, why and how.Technical report, Xerox Parc.

Ferrari, M., Fiorentini, C., and Fiorino, G. (2010).BCDL: basic constructive description logic.J. of Automated Reasoning, 44(4):371–399.

Ferrari, M., Fiorentini, C., Momigliano, A., and Ornaghi, M. (2008).Snapshot generation in a constructive object-oriented modeling language.In LOPSTR 2007, Selected Papers, volume 4915 of Lecture Notes in Computer Science, pages 169–184. Springer.

Fiorentini, C. and Ornaghi, M. (2007).Answer set semantics vs. information term semantics.In ASP2007: Answer Set Programming, Advances in Theory and Implementation.

Haeusler, E. H., de Paiva, V., and Rademaker, A. (2011).Intuitionistic description logic and legal reasoning.In DEXA 2011 Workshops, pages 345–349. IEEE Computer Society.

References III

Hilia, M., Chibani, A., Djouani, K., and Amirat, Y. (2012).Semantic service composition framework for multidomain ubiquitous computing applications.In ICSOC 2012, volume 7636 of Lecture Notes in Computer Science, pages 450–467. Springer.

Kamide, N. (2010a).A compatible approach to temporal description logics.In DL2010 - International Workshop on Description Logics.

Kamide, N. (2010b).Paraconsistent description logics revisited.In DL2010 - International Workshop on Description Logics, pages 197–208.

Kaneiwa, K. (2005).Negations in description logic – contraries, contradictories, and subcontraries.In Dau, F., Mugnier, M.-L., and Stumme, G., editors, Common Semantics for Sharing Knowledge: Contributions to the13th International Conference on Conceptual Structures (ICCS ’05), pages 66–79. Kassel University Press.

Mendler, M. and Scheele, S. (2009).Towards a type system for semantic streams.In SR2009 - Stream Reasoning Workshop (ESWC 2009), volume 466 of CEUR-WP. CEUR-WS.org.

Mendler, M. and Scheele, S. (2010).Towards Constructive DL for Abstraction and Refinement.J. Autom. Reasoning, 44(3):207–243.

Miglioli, P., Moscato, U., and Ornaghi, M. (1986).PAP: A Logic Programming System Based on a Constructive Logic.In Foundations of Logic and Functional Programming, volume 306 of Lecture Notes in Computer Science, pages143–156. Springer.

References IV

Miglioli, P., Moscato, U., Ornaghi, M., and Usberti, G. (1989).A constructivism based on classical truth.Notre Dame Journal of Formal Logic, 30(1):67–90.

Odintsov, S. and Wansing, H. (2003).Inconsistency-tolerant description logic. Motivation and basic systems.In Hendricks, V. and Malinowski, J., editors, Trends in Logic. 50 Years of Studia Logica, pages 301–335. Kluwer AcademicPublishers, Dordrecht.

Odintsov, S. and Wansing, H. (2008).

Inconsistency-tolerant description logic. Part II: A tableau algorithm for CALCC.J. of Applied Logic, 6(3):343–360.

Villa, P. (2010).Semantics foundations for constructive description logics.PhD thesis, DICOM – Università degli Studi dell’Insubria.

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