Day 7: mat385

Last time

Next time

Today:

• Announcements:
  • Reminder: turn off your rectangles.

  • Roll.

  • You have a problem set due today.

    Questions about the homework?

  • Your 1.4 homework is (not) returned.

    • Graded 18, 26, 42 (uh oh, nothin' but evens....):

      • 18: Same trick as I mentioned last time: given \[ (\exists x)[R(x) \lor S(x)] \longrightarrow (\exists x)R(x) \lor (\exists x)S(x) \] replace with \[ (\exists x)[R(x) \lor S(x)] \longrightarrow [((\exists x)R(x))' \longrightarrow (\exists x)S(x) \] and use the deduction method.

      • 26: Pretty straightforward (deduction method)

      • 42: Wicked! It's really important here to write your hypotheses in a form conducive to making the case.

        I want to go over this one (it involves an extensive temporary hypothesis), and I have been gentle as I've been grading it....:)

• Today:

  • Last time we hit chapter 2, section 2: Induction

    We'll start with a look at a few more "fun" examples.

  • Today we hit Recursion.