Math 39 Homework #7 Work is the greatest thing in the world, so we should always save some of it for tomorrow. Don Herald

	Quiz Remember that we have a quiz on Monday 10/12 on Lectures 5 - 7.

	Reading Read what we will cover in the next class: 3.1 & 3.2. When reading 3.1 pay special attention to the following concepts: predicates, universal quantifier, existential quantifier, bound variables, the relationship between the existential and the universal quantifier. When reading 3.2 pay special attention to the following concepts: the alphabet, term, wfs, atomic formulas, scope of quantifier, bound vs free variable term t is free for x.

	Problems The following problems are due by the beginning of class on Monday 10/5. 2.2: 11. Prove that an extension L* of L is inconsistent iff there exists a finite subset of L* that is inconsistent. Prove that an extension L* of L is consistent iff L* is satisfiable. (See HW #5 if you need the definition of satisfiable) Prove that if L* is an extension of L and every finite subset of L* is satisfiable, then L* is satisfiable. Prove that if F is a satisfiable extension of L and A is a wf, then at least one of F U {A} and F U {~A} is satisfiable. Let F be a consistent extension of L. Prove that the following are equivalent: (1) F is complete, (2) F has exactly one model.