/sci/ - Science & Math

>>9068581
Let's put it to the test.
In pic related, according to the first formula, from >>9066908 there should be 16 - 12 + 3 = 7 walks between two points, and according to the second formula, from >>9068026 there should be 1 + 2 + 2 = 5 walks between two points.
According to http://mathworld.wolfram.com/Walk.html a walk is a sequence [math] v_0, e_1, v_1, \dots, v_k [/math] of graph vertices [math] v_i [/math] and graph edges [math] e_i [/math] such that for [math] 1 \leq i \leq k [/math], the edge [math] e_i [/math] has endpoints [math] v_(i-1) [/math] and [math] v_i [/math]. Simple enough.
How many walks between A and D are there?

There's
A, [AD], D
A, [AB], B, [BD], D
A, [AC], C, [CD], D
A, [AB], B, [BC], C, [CD], D
A, [AC], C, [BC], B, [BD], D

Well anon, it looks like your textbook is wrong. I'm assuming it was written by compsci brainlets.