4 Communication

Question 1

MAS

Answer 1

A multi-agent system (MAS) may be seen as a collection of deliberative, autonomous, collaborative agents, that may communicate and cooperate with each other to solve complex distributed problems.

Question 2

Benefits of MAS

Answer 2

• modularity
• efficiency
• reliability
• flexibility

Question 3

Steps of distributed problem solving

Answer 3

1 task decomposition
2 task allocation
3 task accomplishment
(conflict management, task sharing, result sharing)
4 result synthesis

Question 4

communication categories

Answer 4

point to point
broadcast
mediated by a third party

Question 5

communication methods

Answer 5

blackboard systems

direct message passing

Question 6

blackboard

Answer 6

• Detect conflicts
  Different agents that want to perform the same task
• Notice incompatible solutions
  Solutions using a shared resource at the same time
• Share results
  Agents can use partial/complete results obtained by other agents

Share tasks
Agents can request help in solving sub-tasks

Question 7

blackboard

pros and cons

Answer 7

+ Flexible mechanism that allows communication/cooperation
+ Independent of cooperation strategy
+ It does not place any restriction on the agents’ internal architecture

• Centralised structure
• System bottleneck
• Everyone has to write info on the blackboard
• Everyone has to read from the blackboard
• Single point of failure

Question 8

message passing

Answer 8

Information is passed from one agent to another. The nature of this information can be very varied. Speech acts provide one way to describe this variety:

Types of speech act
•	Inform 
•	Query 
•	Answer 
•	request 
•	promise
•	offer
•	acknowledge
agree
refuse
subscribe
propose

In general, a speech act can be seen to have two components:

• a performative verb: (e.g., request, inform, promise, )
• propositional content: (e.g., “the door is open”)

Question 9

ontology

Answer 9

An ontology is an explicit description of a domain . An ontology defines

• a common vocabulary
• a shared understanding of a domain among a set of agents

OWL: Web Ontology Language

Question 10

ontological components

Answer 10

classes
Classes are sets of individuals with common characteristics

subclasses
Defines class specializations by constraining their coverage 

individuals
Individuals are the specific objects in the domain

properties
Properties can be used to state relationships between individuals

subproperties
Defines properties specializations by constraining their coverage

domain
indicates the individuals to which the property is applied

range
indicates the individuals that receive the application of the property

Question 11

OWL

Answer 11

Web Ontology Language

OWL is a language for representing ontologies, which extends frame languages