The proof system Res(lin_R) is an extension of Resolution in which proof lines are disjunctions of linear equations over a ring R. If R is a finite field GF(p), Res(lin_R) can be viewed as a "minimal" fragment of bounded depth Frege system with counting gates AC^0[p]-Frege (and similarly, for R the integers and the TC^0-Frege), for which no nontrivial lower bound is known.
Recent suggested approaches for obtaining lower bounds against Res(lin_GF(2)) refutations include feasible interpolation and combinatorial techniques. In this talk we explore and develop further the combinatorial approach for various rings R. In particular, we prove an exponential-size dag-like Res(lin_F) lower bound for the Subset Sum principle with large coefficients, as well as establish a host of new tree-like lower bounds and separations over different fields.
Based on a joint work with Iddo Tzameret.