INTERACTION AND COMMUNICATION. Coordination A property of interaction among a set of agents...
-
date post
19-Dec-2015 -
Category
Documents
-
view
216 -
download
0
Transcript of INTERACTION AND COMMUNICATION. Coordination A property of interaction among a set of agents...
![Page 1: INTERACTION AND COMMUNICATION. Coordination A property of interaction among a set of agents performing some activity in a shared state. The degree of.](https://reader030.fdocuments.in/reader030/viewer/2022032800/56649d3e5503460f94a16b3c/html5/thumbnails/1.jpg)
INTERACTION AND COMMUNICATION
![Page 2: INTERACTION AND COMMUNICATION. Coordination A property of interaction among a set of agents performing some activity in a shared state. The degree of.](https://reader030.fdocuments.in/reader030/viewer/2022032800/56649d3e5503460f94a16b3c/html5/thumbnails/2.jpg)
CoordinationA property of interaction among a set of agents performing
some activity in a shared state. The degree of coordination is the extent to which they
avoid extraneous activity– reduce resource contention
– avoid livelock
• avoid deadlock
• maintain safety conditions
Cooperation is coordination among nonantagonistic agents. Typically,
• each agent must maintain a model of the other agents
• each agent must develop a model of future interactions
![Page 3: INTERACTION AND COMMUNICATION. Coordination A property of interaction among a set of agents performing some activity in a shared state. The degree of.](https://reader030.fdocuments.in/reader030/viewer/2022032800/56649d3e5503460f94a16b3c/html5/thumbnails/3.jpg)
Coherence and Commitments
• Coherence is how well a system behaves as a unit. It requires some form of organization, typically hierarchical
• Social commitments are a means to achieve coherence
![Page 4: INTERACTION AND COMMUNICATION. Coordination A property of interaction among a set of agents performing some activity in a shared state. The degree of.](https://reader030.fdocuments.in/reader030/viewer/2022032800/56649d3e5503460f94a16b3c/html5/thumbnails/4.jpg)
Communication• The primary reason for communication among
agents is to coordinate activities• Agents may coordinate without communication
provided they have models of the others’ behavior• Communication involves the dimensions of who,
what, when, how (resources and protocol), and why
• To facilitate cooperation, agents often need to communicate their intentions, goals, results, and state
![Page 5: INTERACTION AND COMMUNICATION. Coordination A property of interaction among a set of agents performing some activity in a shared state. The degree of.](https://reader030.fdocuments.in/reader030/viewer/2022032800/56649d3e5503460f94a16b3c/html5/thumbnails/5.jpg)
Communication Versus Computation
• Communication is generally more expensive and less reliable:– Recomputing is often faster than requesting information over a
communication channel
– Communication can lead to prolonged negotiation
– Chains of belief and goal updates caused by communication may not terminate
• Communication is qualitatively superior:– Information cannot always be reconstructed locally
– Communication can be avoided only when the agents are set up to share all necessary knowledge (a limiting assumption)
![Page 6: INTERACTION AND COMMUNICATION. Coordination A property of interaction among a set of agents performing some activity in a shared state. The degree of.](https://reader030.fdocuments.in/reader030/viewer/2022032800/56649d3e5503460f94a16b3c/html5/thumbnails/6.jpg)
Interaction and Communication
• Interactions occur when agents exist and act in close proximity:– resource contention, e.g., bumping into each other
• Communication occurs when agents send messages to one another with a view to influencing beliefs and intentions. Implementation details are irrelevant:
• can occur over communication links– can occur through shared memory
– can occur because of shared conventions
![Page 7: INTERACTION AND COMMUNICATION. Coordination A property of interaction among a set of agents performing some activity in a shared state. The degree of.](https://reader030.fdocuments.in/reader030/viewer/2022032800/56649d3e5503460f94a16b3c/html5/thumbnails/7.jpg)
CIS Communication Protocols• A CIS protocol is specified by the following fields:
– sender
– receiver(s)
– language in the protocol
– actions to be taken by the participants at various stages
• A CIS protocol is defined above the transport layer– not about bit patterns
– not about retransmissions or routing
• A CIS protocol is defined at the knowledge level– involves high-level concepts, such as
• commitments, beliefs, intentions
• permissions, requests
![Page 8: INTERACTION AND COMMUNICATION. Coordination A property of interaction among a set of agents performing some activity in a shared state. The degree of.](https://reader030.fdocuments.in/reader030/viewer/2022032800/56649d3e5503460f94a16b3c/html5/thumbnails/8.jpg)
A Classification of Message Classifications
• Syntactic– distinguish messages based on grammatical forms in natural
language
• Semantic– distinguish messages based on a notion of intrinsic meaning
prohibitive is different from directive, despite syntactic similarity
• Use-based– distinguish messages based on their roles in specific classes of
protocolsassertion is different from acknowledgment
![Page 9: INTERACTION AND COMMUNICATION. Coordination A property of interaction among a set of agents performing some activity in a shared state. The degree of.](https://reader030.fdocuments.in/reader030/viewer/2022032800/56649d3e5503460f94a16b3c/html5/thumbnails/9.jpg)
Speech Act TheorySpeech act theory, initially meant for natural language, views
communications as actions. It considers three aspects of a message:
Locution, or how it is phrased, e.g.,– "It is hot here" or "Turn on the cooler"
• Illocution, or how it is meant by the sender or understood by the receiver, e.g.,– a request to turn on the cooler or an assertion about the temperature
• Perlocution, or how it influences the recipient, e.g.,– turns on the cooler, opens the window, ignores the speaker
Illocution is the main aspect. Speech act theory classifies illocutions in various ways
![Page 10: INTERACTION AND COMMUNICATION. Coordination A property of interaction among a set of agents performing some activity in a shared state. The degree of.](https://reader030.fdocuments.in/reader030/viewer/2022032800/56649d3e5503460f94a16b3c/html5/thumbnails/10.jpg)
Speech Act Theory and CISThe classifications motivate message types in CIS. However,
they are typically
• designed for natural language– rely on NL syntax, e.g., they conflate directives and prohibitives
Most research in speech act theory is about determining how locutions map to illocutions. This is trivial in CIS, since
• the message type is usually explicitly encoded
However, speech act theory can contribute
• by giving a principled basis for studying communication– related to beliefs, intentions, know-how of agents
– can have a formal semantics
![Page 11: INTERACTION AND COMMUNICATION. Coordination A property of interaction among a set of agents performing some activity in a shared state. The degree of.](https://reader030.fdocuments.in/reader030/viewer/2022032800/56649d3e5503460f94a16b3c/html5/thumbnails/11.jpg)
Informing
How can one agent tell another agent something?
• Send the information in a message (message passing)
• Write the information in a location where the other agent is likely to look (shared memory)
• Show or demonstrate to the other agent (teaching)
• Insert or program the information directly into the other agent (master --> slave; controller --> controllee; "brain surgery")
![Page 12: INTERACTION AND COMMUNICATION. Coordination A property of interaction among a set of agents performing some activity in a shared state. The degree of.](https://reader030.fdocuments.in/reader030/viewer/2022032800/56649d3e5503460f94a16b3c/html5/thumbnails/12.jpg)
Querying
How can one agent get information from another agent?
• Ask the other agent a question (message passing)
• Read a location where the other agent is likely to write something (shared memory)
• Observe the other agent (learning)
• Access the information directly from the other agent ("brain surgery")
![Page 13: INTERACTION AND COMMUNICATION. Coordination A property of interaction among a set of agents performing some activity in a shared state. The degree of.](https://reader030.fdocuments.in/reader030/viewer/2022032800/56649d3e5503460f94a16b3c/html5/thumbnails/13.jpg)
Syntax, Semantics, Pragmatics
For message passing
• Syntax: requires a common language to represent information and queries, or languages that are intertranslatable
• Semantics: requires a structured vocabulary and a shared framework of knowledge-a shared ontology
• Pragmatics:– knowing whom to communicate with and how to find them
– knowing how to initiate and maintain an exchange
– knowing the effect of the communication on the recipient
![Page 14: INTERACTION AND COMMUNICATION. Coordination A property of interaction among a set of agents performing some activity in a shared state. The degree of.](https://reader030.fdocuments.in/reader030/viewer/2022032800/56649d3e5503460f94a16b3c/html5/thumbnails/14.jpg)
KQML: Knowledge Query and Manipulation Language
KQML KQML
Agent AgentApplication
Program
![Page 15: INTERACTION AND COMMUNICATION. Coordination A property of interaction among a set of agents performing some activity in a shared state. The degree of.](https://reader030.fdocuments.in/reader030/viewer/2022032800/56649d3e5503460f94a16b3c/html5/thumbnails/15.jpg)
KQML Protocols
Client Server
Client Server
Client Server
Query
Reply
QueryHandle
NextNext
ReplyReply
ReplyReplyReply
Subscribe
Synchronous: a blocking query waits for an expected reply
Asynchronous: a nonblocking subscribe results in replies
Server maintains state; replies sent individually when requested
![Page 16: INTERACTION AND COMMUNICATION. Coordination A property of interaction among a set of agents performing some activity in a shared state. The degree of.](https://reader030.fdocuments.in/reader030/viewer/2022032800/56649d3e5503460f94a16b3c/html5/thumbnails/16.jpg)
KQML Is a Layered Language
Content ofCommunication
Message:Logic of Communication
Communication:Mechanics of Communication
![Page 17: INTERACTION AND COMMUNICATION. Coordination A property of interaction among a set of agents performing some activity in a shared state. The degree of.](https://reader030.fdocuments.in/reader030/viewer/2022032800/56649d3e5503460f94a16b3c/html5/thumbnails/17.jpg)
Communication Assumptions
• Agents are connected by unidirectional links that carry discrete messages
• Links have nonzero transport delay• Agent knows link of received message• Agent controls link for sending• Messages to a single destination arrive in the order
they were sent• Message delivery is reliable
![Page 18: INTERACTION AND COMMUNICATION. Coordination A property of interaction among a set of agents performing some activity in a shared state. The degree of.](https://reader030.fdocuments.in/reader030/viewer/2022032800/56649d3e5503460f94a16b3c/html5/thumbnails/18.jpg)
KQML Semantics
• Each agent manages a virtual knowledge base (VKB)
• Statements in a VKB can be classified into beliefs and goals
• Beliefs encode information an agent has about itself and its environment
• Goals encode states of an agent’s environment that it will act to achieve
• Agents use KQML to communicate about the contents of their own and others’ VKBs
![Page 19: INTERACTION AND COMMUNICATION. Coordination A property of interaction among a set of agents performing some activity in a shared state. The degree of.](https://reader030.fdocuments.in/reader030/viewer/2022032800/56649d3e5503460f94a16b3c/html5/thumbnails/19.jpg)
Reserved Performative Types1. Query performatives:• evaluate, ask-if, ask-one, ask-all
2. Multiresponse performatives:• stream-in, stream-all
3. Response performatives:• reply, sorry
4. Generic informational performatives:• tell, achieve, cancel, untell, unachieve
5. Generator performatives:• standby, ready, next, rest, discard
6. Capability-definition performatives:• advertise, subscribe, monitor, import, export
7. Networking performatives:• register, unregister, forward, broadcast, route, recommend
![Page 20: INTERACTION AND COMMUNICATION. Coordination A property of interaction among a set of agents performing some activity in a shared state. The degree of.](https://reader030.fdocuments.in/reader030/viewer/2022032800/56649d3e5503460f94a16b3c/html5/thumbnails/20.jpg)
Informatives
tell
:content <expression>
:language <word>
:ontology <word>
:in-reply-to <expression>
:force <word>
:sender <word>
:receiver <word>
deny
:content <performative>
:language KQML
:ontology <word>
:in-reply-to <expression>
:sender <word>
:receiver <word>
untell
:content <expression>
:language <word>
:ontology <word>
:in-reply-to <expression>
:force <word>
:sender <word>
:receiver <word>
![Page 21: INTERACTION AND COMMUNICATION. Coordination A property of interaction among a set of agents performing some activity in a shared state. The degree of.](https://reader030.fdocuments.in/reader030/viewer/2022032800/56649d3e5503460f94a16b3c/html5/thumbnails/21.jpg)
Database Informativesinsert
:content <expression>
:language <word>
:ontology <word>
:reply-with <expression>
:in-reply-to <expression>
:force <word>
:sender <word>
:receiver <word>
delete
:content <performative>
:language KQML
:ontology <word>
:reply-with <expression>
:in-reply-to <expression>
:sender <word>
:receiver <word>
![Page 22: INTERACTION AND COMMUNICATION. Coordination A property of interaction among a set of agents performing some activity in a shared state. The degree of.](https://reader030.fdocuments.in/reader030/viewer/2022032800/56649d3e5503460f94a16b3c/html5/thumbnails/22.jpg)
Query Performatives
evaluate
:content <expression>
:language <word>
:ontology <word>
:reply-with <expression>
:sender <word>
:receiver <word>
reply
:content <expression>
:language KQML
:ontology <word>
:in-reply-to <expression>
:force <word>
:sender <word>
:receiver <word>
ask-one
:content <expression>
:aspect <expression>
:language <word>
:ontology <word>
:reply-with <expression>
:sender <word>
:receiver <word>
![Page 23: INTERACTION AND COMMUNICATION. Coordination A property of interaction among a set of agents performing some activity in a shared state. The degree of.](https://reader030.fdocuments.in/reader030/viewer/2022032800/56649d3e5503460f94a16b3c/html5/thumbnails/23.jpg)
Semantics of Communications
What if the agents have• different terms for the same concept?• same term for different concepts?• different class systems or schemas?• differences in depth and breadth of coverage?
![Page 24: INTERACTION AND COMMUNICATION. Coordination A property of interaction among a set of agents performing some activity in a shared state. The degree of.](https://reader030.fdocuments.in/reader030/viewer/2022032800/56649d3e5503460f94a16b3c/html5/thumbnails/24.jpg)
Common Ontologies• A shared representation is essential to successful
communication and coordination
• For humans, this is provided by the physical, biological, and social world
• For computational agents, this is provided by a common ontology:– terms used in communication can be coherently defined
– interaction policies can be shared
• Current efforts are– Cyc
– DARPA ontology sharing project
– Ontology Base (ISI)
– WordNet (Princeton)