Errors detected by Jerry Grossman (as per email of July 14, 2011) page 16, next to last paragraph line 5: "edges" should probably be in the same font as "vertices". page 16, next to last paragraph line 7: "order pair" should be "ordered pair". page 18, second paragraph, line 1: "refers" should be "refer". page 18, third paragraph, line 4: $\cup$ should be $\bigcup$. page 19, first paragraph, line 7: "etc" should be "etc.". page 20, line -3: "let we" should be "let us". page 41, last line of first paragraph of 1.2.4.3: "skiping" should be "skipping". page 41, last line (not counting the footnote): "formula" should be "formulae".