# Thread: last two problems. order relation

1. ## last two problems. order relation

1) Let n be a postive integer. Explain why the set A of all integers greater than or equal to -n is well-ordered. (hint: if B is a nonempty subset of A, consider the set C of all integers of the form n + b where b in b)

2) Determine the number of Boolean subalgebras of P(X) if X is the set {1,2,3,4}. How many have exactly two atomic subsets?

Thank you so much for all the help from this forum.

2. 1) If the order relation to the set A is < (is it?), A has a least element, namely -n. Also every subset of A has a least element, since no of the elements in A equals any other, hence if $a,\ b\ \epsilon\ A$, either a < b or b < a, cause A only contains each integer once.

I hope that was right now!