Class Notes CIS 675 Knowledge and Reasoning CIS 675 c Péter Molnár, 2001 Slide 1
Inference in First-Order Logic (Chapter 9) First-Order Logic (Chapter 7) Agents That Reason Logically (Chaper 6) Knowledge and Reasoning
CIS 675 c Péter Molnár, 2001
Slide 2
Propositional Logic Representation, Reasoning, and Logic A Knowledge-Based Agent I. Agents That Reason Logically
CIS 675 c Péter Molnár, 2001
Slide 3 Agents That Reason Logically TELL(KB, MAKE-PERCEPT-SENTENCE( percept, t)) action ASK(KB, MAKE-ACTION-QUERY(t)) TELL(KB, MAKE-ACTION-SENTENCE(action, t)) t t+1 return action function KB-AGENT( percept) returns an action static: KB, a knowledge base t, a counter, initially 0, indicating time A Knowledge-Based Agent
 Inference mechanism: determine what follows from the sentences that have been added to the KB. Add new sentences, query knowledge: functions A SK and T ELL. Knowledge base (KB): set of representations of facts. Each individual representation id called a sentence of a knowledge representation language.  CIS 675 c Péter Molnár, 2001
Slide 4 Agents That Reason Logically A Knowledge-Based Agent (cont’d) Description of knowledge-based agents in three levels: 1. knowledge level or epistemological level: most abstract, describe agent by saying what it knows. E.g. “An automated taxi knows that the Golden Gate Bridge links San Francisco with Marin County”. 2. logical level: knowledge is encoded into (formal) sentences. E.g. Links(GGBridge, SF, Marin) Representation of knowledge in sentences simplifies the design declarative approach to system building. 3. implementation level: level that runs on the agent architecture; physical representation of sentences on logical level. E.g. string, objects with pointers, or entry in 3-dim. table indexed by road links and location pairs. Implementation of learning mechanisms that produce general knowledge given a series of percepts. CIS 675 c Péter Molnár, 2001 Slide 5 Agen