2. Let D be a relation on the natural numbers N deﬁned by D = {(m,n)...

2. Let D be a relation on the natural numbers N deﬁned by D = {(m,n) : m | n} (i.e., D(m,n) is true when n is divisible by m. For this problem, you’ll be proving that D is a partial order. This means that you’ll need to prove that it is reﬂexive, anti-symmetric, and transitive.

(a) Prove that D is reﬂexive. (Yes, you already did this problem on one of the minihomework assignments. You don’t have to redo the problem, but you should at least copy over your answer from that assignments to this one.)

(b) Prove that D is anti-symmetric. You may use the following fact: for any two natural numbers m and n, if m·n = 1, then m = 1 and n = 1. (Note that D is only anti-symmetric because the domain is the natural numbers. If we switched to the domain of integers, then things would be completely diﬀerent.)

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Colby Messinger answered 11 months ago

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