PREDICATE LOGIC

Review:

	Represent concepts as symbols
		e.g.	S = "stench in this square",
			W = "wumpus in this square",
			OK = "no danger in this square"...)

	statements use Boolean connectives to indicate relations 
		between symbols

Basic Boolean connectives

	and, or, not, if-then, if-and-only-if
		(e.g. A and B, A or B, if A then B, A if-and-only-if B)

Syntax of Predicate Logic

	 ->   
	 -> not 
	 -> 
	 -> and, or, if-then, if-and-only-if
	 -> a, b, S, W, noun, verb, ...

Sentences Combining Basic Connectives

	if S(1,2) and OK(1,1) and OK(2,2) then W(1,3)

	if S(x, y) and OK(x, y-1) and OK(x+1, y) and OK(x-1, y) 
	then W(x, y+1)

	if S(x, y) and OK(x, y+1) and OK(x+1, y) and OK(x-1, y) 	
	then W(x, y-1)

Prolog and Declarative Programming

	richer version of this



			INFERENCE IN PROPOSITIONAL LOGIC

Modus Ponens (Implication Elimination)

And Elimination

And Introduction

Or Introduction

Double-Negation Elimination

Unit Resolution

Resolution



		PREDICATE LOGIC AS A KNOWLEDGE REPRESENTATION

Advantages

	relatively easy to represent ideas

	Boolean connectives can be efficiently evaluated

	many people have experience with predicate logic

Disadvantages

	must talk about specific instances, rather than classes of 
	concepts and relations

	does not support partial truth values

	does not support belief values