linear algebra 08/18/2017 lecture 12

lecture 12:
graph:
node - edge graph A (column 是 node; row 是edge)
现在看A的 null space

Euler's formula:
#nodes-#edges+#loops = 1

lecture 13:

u,v,w in Rt 构成一个 5*3 u  rank = 3
N(u) = n-r = 0 只有零向量


r = m or r = n (full rank matrix )