一句话:建立卵石游戏与代数证明系统 NS/MC/PC 的对应,导出度数分离与度数-规模权衡。
论文分析卵石公式 Peb(G) 的代数反驳,建立卵石游戏与代数证明系统的强联系:可逆、黑、黑白卵石游戏分别对应 Nullstellensatz、Monomial Calculus 与 Polynomial Calculus。对单汇 DAG G,作者证明 MC 反驳的度数 s 与规模 t 对应于黑卵石策略的空间 s 与时间 t+s,反向则可提取度数 s、规模 ts 的 MC 反驳,类似 de Rezende 等关于可逆卵石与 NS 的结果。由此得到 NS、MC、PC 的度数分离、MC 的度数-规模权衡;并证明三种卵石游戏空间恰等于对应系统反驳的变量空间复杂度,结合已知卵石界导出变量空间分离。
Analyzing refutations of the well known 0pebbling formulas Peb$(G)$ we prove some new strong connections between pebble games and algebraic proof system, showing that there is a parallelism between the reversible, black and black-white pebbling games on one side, and the three algebraic proof systems Nullstellensatz, Monomial Calculus and Polynomial Calculus on the other side. In particular we prove that for any DAG $G$ with a single sink, if there is a Monomial Calculus refutation for Peb$(G)$ having simultaneously degree $s$ and size $t$ then there is a black pebbling strategy on $G$ with space $s$ and time $t+s$. Also if there is a black pebbling strategy for $G$ with space $s$ and time $t$ it is possible to extract from it a MC refutation for Peb$(G)$ having simultaneously degree $s$ and size $ts$. These results are analogous to those proven in {deRezende et al.21} for the case of reversible pebbling and Nullstellensatz. Using them we prove degree separations between NS, MC and PC, as well as strong degree-size tradeoffs for MC. We also notice that for any directed acyclic graph $G$ the space needed in a pebbling strategy on $G$, for the three versions of the game, reversible, black and black-white, exactly matches the variable space complexity of a refutation of the corresponding pebbling formula Peb$(G)$ in each of the algebraic proof systems NS, MC and PC. Using known pebbling bounds on graphs, this connection implies separations between the corresponding variable space measures.