logic

We have six statements about a number, and we know that exactly 1 is false.

  1. I am greater than 50
  2. I am a multiple of 7
  3. I am a perfect square
  4. I am a 3-digit number
  5. I am less than 500
  6. I am a multiple of 17

Are there any numbers that fit? How many? And if they exist, what are they?

Unrelated, interesting note: Nice factoring techniques for solving problems such as

Find n such that n(n+16) is a perfect square

are presented at the Ultimate Quant Marathon Blog for IIM Cat (whatever that means), a brand new blog. I think it’s called Quantologic for short.

I teach a logic course (elective) in high school.

(Link at bottom to paper on history of logic text books!)

In past years it has been open to juniors and seniors; this year, because of slightly greater demand, there are seniors only. It is one term. In our school major subjects meet four days each week (extended periods). We award one math credit (a NYC credit is equivalent to half a credit elsewhere in New York State).

The grading guidelines are generous. And one day of every four is devoted to games or puzzles (for example, we examined Monty Hall last week. We played 3d tic tac toe the week before. And we solved LSAT logic games the week before that.

But the content? More or less what I learned in logic 101 at Brooklyn Polytech, and with the same text (Hurley). But look, there’s more texts out there. Sitting on my shelf are introductory books by Suppes, Tarski, Smullyan (and Copi at work). Dusty though.

In fact, I am violating my own philosophy of teaching math… I don’t know enough about logic to be teaching it. Summer reading. And a real course. My evening employer has a highly-regarded logician on staff. I will get advice (course recommendation?)

Back to texts. Myrtle asked me about logic, including which text we use, and was not familiar with Hurley. I found a great paper from by Francis Jeffrey Pelletier of San Diego State, comparing methods of proof in 3 dozen major texts (including Copi, Suppes, Hurley). A History of Natural Deduction and Elementary Logic Textbooks. If you don’t have the patience to read it all (ok, me neither), the intro tells the story of two mathematicians getting natural deduction rolling, independently, in 1934. And then on page 31 is an interesting comparison of the texts. The differences in approach to proof are relatively recent.

Introduction to Logic A Concise Introduction to Logic (with CD-ROM) (Concise Introduction to Logic)Copi, or Hurley, or something else? Why?

Introductory course (for mildly motivated, fairly bright high school seniors).  One term. Three one hour meetings per week, about 17 weeks. An additional hour per week reserved for games and puzzles.

Any ideas? Suggestions? Relevant experience?

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