In todays lecture I spoke ¡­

In todays lecture I spoke about equivalence relations and partitions, congruences mod N, and defined addition and multiplication of congruence classes. This corresponds to the last part of section 0 in the book.

On Friday, I'll do the motivating example (notes are posted) and start on section 4, the definition of groups. I'll mention some of the topics in section 2 and 3, but will not use to much time on it.

Roots of unity wil pop up frequently, so if you are not at ease with that, you should read section 1.

G