一句话:刻画 Sherali-Adams 与 Nullstellensatz 相对于 Frege 类系统及树状/一般 Resolution 的证明强度。
本文研究代数证明系统 Sherali-Adams (SA) 与 Nullstellensatz (NS) 相对于 Frege 类系统的强度。已知 SA 能多项式规模证明鸽巢原理,而 bounded-depth Frege 不能,因此自然的问题是 bounded-depth Frege 加入 SA 是否足以模拟 SA。作者用 Frege 风格系统刻画二者强度,证明带一元整数系数的 SA 严格位于树状 Resolution 与 Resolution 之间;并引入加权版本,证明带整数系数的加权 SA 也严格位于二者之间。对 NS,则借助双射鸽巢原理及其加权版本得到类似刻画。
We characterize the strength of the algebraic proof systems Sherali-Adams () and Nullstellensatz () in terms of Frege-style proof systems. Unlike bounded-depth Frege, has polynomial-size proofs of the pigeonhole principle (). A natural question is whether adding to bounded-depth Frege is enough to simulate . We show that , with unary integer coefficients, lies strictly between tree-like and tree-like Resolution. We introduce a weighted version of () and we show that with integer coefficients lies strictly between tree-like and Resolution. Analogous results are shown for using the bijective (i.e. onto and functional) pigeonhole principle and a weighted version of it.