Math 470 Spring ’05

Optional HW #6a Due 4/4

Any problems from Section 2.7 pp 125-126

And

Consider the language L = {0, 1, +, *, <} and four structures –
N =the natural numbers (with 0),
Z = the integers (positive, negative, 0)
Q = the rationals
R = the reals
with the standard interpretations of the symbols of L.
Since we have 4 structures and a sentence can be true or false in each, there are 16 possible combinations of truth values.
See if you can find one sentence in each of the 16 categories; i.e., one true in all four structures, one true in N and false in all the others, ...