Example
The position analyzer on Connect 4, 4,000 simulations. Column 4 is the only move that sets up two threats at once.
. . . . . . .
. . . . . . .
. . . . . . .
. . . . . . .
. O O . . . .
. X X . . . .
1 2 3 4 5 6 7
Action Visits Share Mean
------ ------ ------ -----
4 3414 85.4% 0.888
1 157 3.9% 0.627
3 144 3.6% 0.615
2 108 2.7% 0.560
5 64 1.6% 0.445
7 61 1.5% 0.434
6 52 1.3% 0.385
Principal variation: 4 -> 1 -> 5
Results
Connect 4 against a random player, 100 games per budget, 50 from each seat.
| simulations per move | UCT win rate | Flat UCB win rate |
|---|---|---|
| 1 | 45% | 45% |
| 4 | 56% | 45% |
| 8 | 91% | 93% |
| 32 | 95% | 98% |
| 128 | 100% | 100% |
What’s in it
games tic-tac-toe · Connect 4 · 6×6 checkers · dots and boxes · 2048 (chance nodes)
search UCT · Flat UCB (UCB1 at the root only) · per-game rollout policies
tools round-robin arena with Elo · position analyzer · tree visualizer · terminal and pygame UIs