Computer Science 25/10/20151 Agent Communication BDI Logic CPSC /CPSC Rob Kremer Department of Computer Science University of Calgary Based on: FIPA. FIPA Communicative Act Library Specification. Foundation for Intelligent Physical Agents, Document number SC00037J, Document source FIPA TC Communication

25/10/2015CPSC /599.68: Agent Communications2 Basics First order model logic with identity Three primitive attitudes: B i pi (implicityly) believes p U i pi is uncertain about p but thinks that p is more likely than ¬p C i p(choice) i desires that p currently holds Other attitudes: PG i pi has p as a persistent goal (desire?) I i pi has the intention to bring about p

25/10/2015CPSC /599.68: Agent Communications3 Actions a 1 ; a 2 sequence in which a 2 follows a 1. a 1 | a 2 nondeterministic choice in which either a 1 happens or a 2 happens, but not both. Feasible(a,p) a can take place and, if it does, p will be true just after that. (Feasible(a)  Feasible(a, True) Possible(p)   a.Feasible(a,p). Done(a,p)a has just taken place and p was true just before that. (Done(a)  Done(a,True) Agent(i,a)i is the only agent that ever performs (in the past, present or future) the actions a. Single(a)a is not a sequence. ¬Single(a 1 ;a 2 ), but Single(a 1 |a 2 ) iff Single(a 1 )/\Single(a 2 )

25/10/2015CPSC /599.68: Agent Communications4 Abbreviations Bif i p  B i p \/ B i ¬p Bref i l x  (x)   y.B i ( l x  (x) = y). Agent i believes that it knows the (x which is) . Uif i p  U i p \/ U i ¬p Uref i l x  (x)   y.U i ( l x  (x) = y). AB n,i,j p  B i B j B i …p. n is the number of B operators alternating between i and j.

25/10/2015CPSC /599.68: Agent Communications5 Property: intending to achieve a RE ⊨ (  x. B i a k =x)// there exists an action /\ RE(a k )=p // who’s RE is p /\ ¬C i ¬Possible(Done(a k ))// that i thinks should be done  (I i p  I i Done(a 1 | … |a n )// then if i intends p, then i intents one of the act that can achieve it “If I intent to break the vase, then I intent to either drop it, or smash it with a hammer”

25/10/2015CPSC /599.68: Agent Communications6 Property: satisfiability of intent ⊨ I i Done(a)  B i Feasible(a) \/ I i B i Feasible(a) If agent i intends a, then it needs to believe a is feasible or at least have the intent to discover if a is feasible “If I intend to build a perpetual motion machine, then I have to believe it’s possible or to at least discover if it’s possible.”

25/10/2015CPSC /599.68: Agent Communications7 Property: intent of act implies intent of RE ⊨ I i Done(a)  I i RE(a) If agent i intends a, then it also intents the RE of a “If I intend to drop the vase, then I also intend to break the vase”

25/10/2015CPSC /599.68: Agent Communications8 Property: observing an act ⊨ B i (Done(a) /\ Agent(j,a)  I j RE(a)) If agent i observes j doing a, then i will come to believe the j intends the RE of a. “If I see Jane hammering the vase, then I believe that Jane intends to break the vase”