==========[Example #1]========== The full game tree is: o / | \ o o o / \ / \ / \ o o o o o o | | | | | | o o o o o o Branching factor: (3 + 3*2 + 3*2*1) / (1 + 3 + 3*2) = 15 / 10 = 1.5 If the middle branch is symmetric with one of it siblings. The game tree becomes: o / \ o o / \ / \ o o o o | | | | o o o o Branching factor: (2 + 4 + 4) / (1 + 2 + 4) = 10 / 7 = 1.43 < 1.5 ==========[Example #2]========== The full game tree: o / / \ \ o o o o / | \ / | \ / | \ / | \ o o o o o o o o o o o o / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ o o o o o o o o o o o o o o o o o o o o o o o o | | | | | | | | | | | | | | | | | | | | | | | | o o o o o o o o o o o o o o o o o o o o o o o o Branching factor: (4 + 4*3 + 4*3*2 + 4*3*2*1) / (1 + 4 + 4*3 + 4*3*2) = 64 / 41 = 1.56 If the two branches on the right side are symmetric to their siblings, and a couple of the inner branches are symmetric to their siblings. The game tree becomes: o / / o o / \ / | \ o o o o o / \ / \ / \ / / o o o o o o o o | | | | | | | | o o o o o o o o Branching factor: (2 + 5 + 8 + 8) / (1 + 2 + 5 + 8) = 23 / 16 = 1.44 < 1.56