For each of the statements, begin a proof by contraposition and
a proof by contradiction. This will include rewriting the
statement, writing the assumptions, and writing what needs to be
shown. From there, pick one of the two methods and finish the
proof.
a) For all integers m and n, if m + n is even the m and n are
both even or m and n are both odd.
b) For all integers a, b, and c, if a...