We analyze strategic complexity across all 960 Chess960 (Fischer Random Chess) starting positions. Stockfish evaluations show a near-universal first-move advantage for White ($\langle E \rangle = +0.30 \pm 0.14$ pawns), indicating that the advantage conferred by moving first is a robust structural feature of the game. To quantify decision difficulty, we introduce an information-based measure $S(n)$ describing the cumulative information required to identify optimal moves over the first $n$ plies. This measure decomposes into contributions from White and Black, $S_W$ and $S_B$, yielding a total opening complexity $S_{\mathrm{tot}} = S_W + S_B$ and a decision asymmetry $A=S_B-S_W$. Across the ensemble, $S_{\mathrm{tot}}$ varies by a factor of three, while $A$ spans from $-2.5$ to $+1.8$ bits, showing that some openings burden White and others Black. The mean $\langle A \rangle = -0.25$ bits indicates a slight tendency for White to face harder opening decisions. Standard chess (position \#518, \texttt{RNBQKBNR}) exhibits above-average asymmetry (91st percentile) but typical overall complexity (47th percentile). The most complex opening is \#226 (\texttt{BNRQKBNR}), whereas \#198 (\texttt{QNBRKBNR})is the most balanced, with both evaluation and asymmetry near zero. These results reveal a highly heterogeneous Chess960 landscape in which small rearrangements of the back-rank pieces can significantly alter strategic depth and competitive fairness. Remarkably, the classical starting position-despite centuries of cultural selection-lies far from the most balanced configuration.
翻译:我们分析了全部960种Chess960(菲舍尔随机象棋)初始局面的战略复杂度。Stockfish评估显示白方在首步移动中具有近乎普遍的优势($\langle E \rangle = +0.30 \pm 0.14$ 兵),表明先手优势是该游戏稳定的结构特征。为量化决策难度,我们引入基于信息的度量 $S(n)$,用于描述前 $n$ 步内识别最优走法所需的累积信息量。该度量可分解为白方与黑方的贡献 $S_W$ 和 $S_B$,由此得到开局总复杂度 $S_{\mathrm{tot}} = S_W + S_B$ 及决策不对称性 $A=S_B-S_W$。在所有局面中,$S_{\mathrm{tot}}$ 存在三倍差异,而 $A$ 的取值范围为 $-2.5$ 至 $+1.8$ 比特,表明某些开局对白方构成负担,另一些则对黑方构成负担。均值 $\langle A \rangle = -0.25$ 比特表明白方在开局决策中面临稍高的难度。标准国际象棋(局面 \#518,\texttt{RNBQKBNR})表现出高于平均水平的不对称性(第91百分位)但具有典型的总体复杂度(第47百分位)。最复杂的开局是 \#226(\texttt{BNRQKBNR}),而 \#198(\texttt{QNBRKBNR})是最均衡的局面,其评估值与不对称性均接近零。这些结果揭示了Chess960局面具有高度异质性,底排棋子的微小重排会显著改变战略深度与竞技公平性。值得注意的是,经典初始局面——尽管历经数个世纪的文化选择——仍远未达到最均衡的配置。