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Specifying Protocols For Knowledge Transfer
and Action Restriction in Multiagent Systems
Marı́a Adela Grando and Christopher Walton
Centre for Intelligent Systems and their Applications (CISA),
Informatics, University of Edinburgh, UK.
CIA Workshop - September 2006
Adela Grando & Chris Walton
MAPa
September 2006
1
Agent Communication
• GOAL: provide effective communication is large Multiagent Systems.
• Existing Approaches:
1. Social Systems ← Control the Chaos.
2. P2P Techniques ← Provide System Scalability.
• Our LCC/MAP Protocol Language:
1. Lightweight Calculus ← Identify Foundations.
2. Executable Specification ← Provide an Implementation.
3. Formal Semantics (Process Calculus) ← Permit Semantic Verification.
Adela Grando & Chris Walton
MAPa
September 2006
2
LCC/MAP Abstract Syntax
P
::=
n(r {M})+
M
::=
method(φ(k) ) = op
op
::=
|
|
|
|
|
α
op1 then op2
op1 or op2
op1 par op2
do op1 timeout op2
call(φ(k) )
::=
|
|
ǫ
ρ(φ(k) ) => agent(φ1 , φ2 ) ← C
C ← ρ(φ(k) ) <= agent(φ1 , φ2 )
(No Action)
(Send)
(Receive)
::=
|
::=
::=
¬C | C ∧ C | C ∨ C
v = p(φ(k) )
a | r | c:τ | v:τ | _
utype | atype | rtype | tname
(Constraint)
(Procedure)
(Terms)
(Types)
α
C
φ
τ
Adela Grando & Chris Walton
(Protocol)
(Method)
(Action)
(Sequence)
(Choice)
(Parallel)
(Iteration)
(Replication)
MAPa
PAR
THEN
OR
CALL
=>
SEND
<=
RECEIVE
September 2006
3
Issues with LCC/MAP Protocols
• Startup issues with LCC/MAP protocols:
1.
2.
3.
4.
5.
How do we engineer agents for specific roles?
How do agents inform their decision making processes?
How do we disseminate protocols among groups of agents?
How can we know that an agent can fulfil a specific role?
How can we identify agents with specific capabilities?
• Considerations for MAPa:
1. Require a way to represent knowledge within protocols.
2. A computationally tractable language (not epistemic logics).
3. Would like to keep the language lightweight.
Adela Grando & Chris Walton
MAPa
September 2006
4
Public and Private Knowledge
I AM
ABLE TO
PAY 380
WILL YOU
ACCEPT
350 ?
OK
I CAN
DROP TO
320
400
Adela Grando & Chris Walton
MAPa
September 2006
5
Scene Knowledge
I WANT TO
JOIN YOUR
AUCTION
Adela Grando & Chris Walton
HERE ARE
THE
RULES
MAPa
SCENE
KNOWLEDGE
September 2006
6
Role Knowledge
I WANT TO
BE A CAR
SELLER
Adela Grando & Chris Walton
HERE IS
WHAT YOU
NEED
MAPa
ROLE
KNOWLEDGE
September 2006
7
MAPa Language Syntax
hR(i) , P (i) , M (k) , K (b) i
hid, P roc(l) , K (m) , r (n) i
(Scene)
(Agent)
::=
agent(id, r, P roc(l) , K (m) , φ(f ) ) = op.
type :: id((φ, type)(g) )
M
::=
id((φ, type)(h) )
(Performative)
op
::=
|
|
|
|
|
v
α
op1 then op2
op1 or op2
op1 par op2
(op)
(Variable)
(Action)
(Sequence)
(Choice)
(Parallel)
(Precedence)
α
::=
null
S
::=
R
::=
P
::=
P roc
(Procedure)
(No Action)
|
v = p(φ(g) )
id(φ(x) ) ⇐ agent(id, r)
id(φ(y) ) ⇒ agent(id, r)
|
agent(id, r, P roc(w) , K (v) , φ(d) )
(Invocation)
c| |v
axiom
(Term)
(Knowledge)
|
|
φ
K
(Role)
::=
::=
Adela Grando & Chris Walton
MAPa
(Decision)
(Receive)
(Send)
September 2006
8
Conclusions and Further Work
• MAPa provides a lightweight way to express the intersection between
communication and knowledge transfer in MAS.
• Possible Future Extensions:
1.
2.
3.
4.
Contracts - specify commitments that agents must adhere to.
Deontics - specify permissions that the agents must follow.
Security - enable secure transfer of information between agents.
Trust - obtain a measure of reliability for the agents in the system.
Adela Grando & Chris Walton
MAPa
September 2006