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Knowledge, Rationality, & Action. Courtesy of Prof. Wiebe van der Hoek Computer Science The University of Liverpool United Kingdom.
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Knowledge, Rationality, & Action Courtesy of Prof. Wiebe van der Hoek Computer Science The University of Liverpool United Kingdom
``..eventually, when you put enough feelingless calculations together in a huge coordinated organization, you’ll get something that has properties on another level. You can see it .... as a system of tendencies and desires and beliefs and so on’’ Hofstadter, 1981, Scientific American Agents’ Paradigm
sense sense act act goal info sense act sense-plan-act cycle (Agents) plan
sense sense act act goal info sense act sense-plan-act cycle (MAS) plan
Rationality A B B A A A 1 4 $4 $3 $1 $5 $2 $4 $7 $3 $6 $5 $1 for A $6 for B
Rationality A B B A A A 1 4 4 3 1 5 2 4 7 3 6 5 $1 for A $6 for B
Rationality A B B A A A 1 4 4 3 1 5 2 4 7 3 6 5 $1 for A $6 for B
Rationality A B B A A A 1 4 4 3 1 5 2 4 7 3 6 5 $1 for A $6 for B
Rationality A B B A A A 1 4 4 3 1 5 2 4 7 3 6 5 $1 for A $6 for B
Rationality A B B A A A 1 4 4 3 1 5 2 4 7 3 6 5 $1 for A $6 for B
Rationality A B B A A A 1 4 4 3 1 5 2 4 7 3 6 5 $1 for A $6 for B
K(f y) (Kf Ky) agents reason logically Kf f veridicality Kf KKf positive introspection ¬Kf K¬Kf negative introspection Epistemic Logic Relies on 4 Axioms
Multiagent Knowledge KAm: A knows m A sends m to B KAm ? KBm ? Em ? KAKB m? KBKAKB m? KAKBKAKB m, ..., Cm?
Knowledge : Monica and Chandler are ... ¬: they are just friends
Nested Knowledge Post: Kc, Km, Kj E{cmj} , E{cmj}E{cmj} E{cmj} (¬Kr & ¬Kp &¬Kro) Goal{m,c}(¬Kr & ¬Kp &¬Kro) Goalj(Kr & Kp &Kro)
Rachel Finds Out … • Pre: • Kj, ¬Kr, Br • ¬KjKr, ¬Kj ¬Kr
Rachel Found Out • Pre: • Kj, ¬Kr, Br • ¬KjKr, ¬Kj ¬Kr • Post: • Kj, Kr, • KjKr, KrKj, • E{j,r}, E{j,r} E{j,r}
Phoebe Found Out • Pre: • Kj, Km, Kp, Kr • E{j,r,p}, • ¬E{j,r,p}E{j,r,p} Let us call this team the Friends team (r, p, and j) and let {c, m, and j } be the Lovers team: ¬EFEF
Phoebe Found Out • Pre: • Kj, Km, Kp, Kr, Kc • EF, • ¬EFEF • Post: • EFEF • ¬KmEF, ¬KcEF • ¬ELEF, Goalp ¬ELEF, Goalj ELEF (Phoebe tries to seduce Chandler)
m and c Learn EF • Post: • EFEF • ¬KmEF, ¬KcEF • ¬ELEF (Chandler tells Monica about the attempted seduction)
m and c Learn EF • Pre: • EFEF • ¬KmEF, ¬KcEF • ¬ELEF • Post: • KmEF, KcEF • EL EF • ¬EF EL EF
p and r Learn EL EF • Pre: • KmEF, KcEF • EL EF • ¬EF EL EF, BF EL EF
p and r learn EL EF • Pre: • KmEF, KcEF • EL EF • ¬EF EL EF, BF EL EF • Post: • EF EL EF • ¬E LEFELEF
Common Knowledge • Ej: Everybody knows j • Ej EEj • Cj: it is Common Knowledge that j • idea: Cj = Ej & EEj & EEEj & EEEEj & ….. • so: ¬Cj if somebody • considers it possible that • somebody considers it possible that somebody considers it possible that …………. j does not hold
Enemies “The message is, that There are known knowns, there are things we know that we know. There are known unknowns, that is to say, there are things that we now know, we don’t know. But there are also unknown unknowns—there are things we do not know we don’t know. And each year, we discover a few more of those unknown unknowns.’’ Play
Foot in Mouth Award • “Despite Mr. Rumsfeld’s rather outlandish mode of speaking, fans of the though-talking US defence secretary argue he is misunderstood.”
Knowledge, Rationality, Action • Knowledge • about world, other’s knowledge, & rationality • uncertainty, beliefs, suspicion • dynamic aspects: updating, learning • Rationality • optimize utilities, do what is best/most economic • Action • emphasis on choice • abilities: physical (robots), computational • epistemic actions