- Hand back homework 2.1. Graded #2, 40, 65
- converse -- Jaime did a nice proof of half, using the temporary hypothesis (worth seeing!)
-
is irrational -- by contradiction. This is exactly the same proof as Example 11, p. 95. If you'd done the reading....
Some claimed that both numerator and denominator of the reduced fraction must be odd -- why? [John and Patrick and Josh have it....]
- Sum of a rational and irrational is irrational. Proven by contradiction. [Michael S. has it.]
- Hand in homework over 2.2.
- Your 2.4 homework is due next time (Monday).
- New assignment over 2.5 (due next Wednesday).
- For those of you thinking about a project (perhaps without
success) let me propose a strategy you could try (suggested by the
lecture of Whitfield Diffie):
Pick some algorithm in which errors propogate (e.g. prime factorization);
Study the question of how to guess which error someone made (from a given family of possible errors), given their (incorrect) result, as well as the correct result.
How can you do the best job of guessing their error possible?
This is related to "check digit" schemes in UPCs, barcodes, etc., in which single digit errors are easily caught.