dp1_v,j is the old value
dp1_v,j is the old value
if you just explain the following i may get enough hint to understand .
according to point C , dp2_u,j = dp1_v,i * dp1_u,i . Let us take following graph , then let us take leg p1 and leg p2 of length 2 from u and v respectively . How they form fork ?
that happens when we combine into u