In this examples of page 32
===========
a = [ 0, 1, 0, 1]
b = [ 1, 0, 1, 0]
c = [ 0, 1, 1, 0]
d = [.5, 0,.5, 0]
e = [-1, 1, 0, 0]

w_sum(a,b) = 0
w_sum(b,c) = 1
w_sum(b,d) = 1
w_sum(c,c) = 2
w_sum(d,d) = .5
w_sum(c,e) = 0
=============

the weighted sum of (c,e) is wrong.

The vector e should be [0, 1, -1, 0] or its negated version
to be consistent with the explanation that follows.

I just noticed that error too.

Also my interpreter was complaining about line:

for i in range(a):  //TypeError: 'list' object cannot be interpreted as an integer

Python 3

fixed with:

for i in range(0, len(a)):