Monday Sep 25

Reiteration: "A => B" meaning more in English (actual causation) than it does in mathematese.

First taste of sets: they are determined by their elements, with no concept of order or repetition. Just in or out.
So {3,7} = {7,3} or {3,7,3,3,7}, but not {7} or {3,{7}}.
Set-forming notation.
Definition. A graph G is a pair of sets V_G, E_G where each element of E_G is a pair of (two different) elements of V.
(Frequent construction: "Definition. An X (noun) is a Y that Z.")
Definition. The degree of a vertex... a couple of versions.
Definition. A graph is regular if all vertices have the same degree... also a couple of versions.
(Frequent construction: "Definition. An X is Y (adjective) if it does Z.")