A computer grammar is described which includes most of the English relative-clause constructions. It is written in the form of a left-to-right phrase-structure grammar with discontinuous constituents and subscripts, which carry such syntactic restrictions as number and verb government category. The motivation for the hierarchy of syntactic choices and for the use of discontinuous constituents i...

We present a novel theorem proving method based on the idea of never combining parts of different assertions (clauses) into a single assertion. This avoids some comb ina,. torial problems with other existing strategies. We mention some refinements of this idea which improve its performance. Results of an implementation are discussed, including tests on logic puzzles, set theory problems, and te...

Quoted speech is often set off by punctuation marks, in particular quotation marks. Thus, it might seem that the quotation marks would be extremely useful in identifying these structures in texts. Unfortunately, the situation is not quite so clear. In this work, I will argue that quotation marks are not adequate for either identifying or constraining the syntax of quoted speech. More useful inf...

Monotone 3-Sat-4 is a variant of the satisfiability problem for boolean formulae in conjunctive normal form. In this variant, each clause contains exactly three literals—either all or none of them are positive, i. e., no clause contains both a positive and a negative literal—and every variable appears at most four times in the formula. Moreover, every clause consists of three distinct literals....

Role and Reference Grammar (RRG) contains a theory of the syntax and semantics of clause linkage. This theory was first developed in Foley & Van Valin (1984) but remained relatively unrevised through the end of the 1990s. In the last five years there has been a flurry of new work on clause linkage, including a substantial revision and expansion of the theory in Van Valin (2005). This paper summ...

This paper introduces Stochastic Definite Clause Grammars, a stochastic variant of the wellknown Definite Clause Grammars. The grammar formalism supports parameter learning from annotated or unannotated corpora and provides a mechanism for parse selection by means of statistical inference. Unlike probabilistic contextfree grammars, it is a context-sensitive grammar formalism and it has the abil...

Generalizing the novel clause elimination procedures developed in [1], we introduce explicit (CCE), hidden (HCCE), and asymmetric (ACCE) variants of a procedure that eliminates covered clauses from CNF formulas. We show that these procedures are more effective in reducing CNF formulas than the respective variants of blocked clause elimination, and may hence be interesting as new preprocessing/s...

Finite domain propagation solvers effectively represent the possible values of variables by a set of choices which can be naturally modelled as Boolean variables. In this paper we describe how we can mimic a finite domain propagation engine, by mapping propagators into clauses in a SAT solver. This immediately results in strong nogoods for finite domain propagation. But a naive static translati...

This work presents a novel strategy for improving SAT solver performance by using concurrency. Rather than aiming to parallelize search, we use concurrency to aid a conventional CDCL search procedure. More concretely, our work extends a conventional CDCL SAT solver with a second computation thread, which is solely used to strengthen the clauses learned by the solver. This provides a simple and ...