Day 4, Mat385

Last time

Next time

Announcements
- This session will be captured on Zoom, if I remember to turn it on, and record it. Please help me to remember.
  Here's a menu of our past zooms...
- A reminder that you had a homework due yesterday at midnight (to submit on Canvas), over Section 1.1. I got 18/24 responses, and a couple of mea culpa emails. What about the rest of you? Are there any particular issues?
  Your next one is due Monday at midnight over section 1.2.
  For this assignment I'm grading the problems (randomly selected)
  1. 15cde
  2. 41ac
  3. 47
- Roll (anyone need to fill out a card?)
Last time:
- We finished up Section 1.1 (Statements, Symbolic Representations, and Tautologies), which we examine using the highlight worksheet 1.1.
- Then it was on to highlight worksheet 1.2: Propositional Logic -- and we got through most of that.
Which brings us to today:
1. I want to start by working problem #51 from section 1.1 -- related to your homework problems, 47-49 (I had several questions on those).
  The somewhat surprising fact is that just one logical connective suffices. Our recursive definition of wffs becomes so much slicker....
  How wasteful we are to use five connectives, when just one suffices!:)
2. Then we'll wrap up Section 1.2
3. Then it's on to Section 1.3 (Quantifiers, Predicates, and Validity), using this highlight worksheet 1.3
Links:
- To prove you're smart, know some math!
- Maybe a little more than you want to know about Propositional Logic. "In 1917, French logician Jean Nicod discovered that it was possible to axiomatize propositional logic using the Sheffer stroke and only a single axiom schema and single inference rule."

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