Due in class Monday September 23

Section 1.2.1: #1 (don’t find the center), #2 (just do the first three: .)
Section 1.2.2: #1(acd), #3
Section 1.3.1: #1 (the problem here is to list the trees up to isomorphism — so any tree with seven vertices should be isomorphic to one from your list, and no two trees on your list should be isomorphic to each other.  Think about how you can organize your search to be sure that you have found all of the trees.)
Section 1.3.2: #1(abcd), #3, #5  (Hint on #3: what happens if you remove a vertex of maximal degree?)

Extra Credit: 1.2.1 #5, #8(d), 1.2.2 #4, 1.3.2 #11