Day 9: mat385

• 2.1 homework returned: graded #14, 17, 35
  • 14: $x=2m+1$ is the definition of oddness, where $m$ is an integer.
  • 17: if you assume $x=2m$, and $y=x+1$, then you also need to assume $x=2m+1$ (or use Example 9, which one wily student did!).

    A couple of you thought you had a counterexample -- but 0 is even!

  • #35: You really should use commutativity..., and start from the "perfect squares".

and we began section 2.4: Recursion.

We'll finish that up first.