Direct automated inversion of logic grammars

Magic for filter optimization in dynamic bottom-up processing

“…Magic compilation is illustrated on the basis of the simple logic grammar extract in figure 1. This grammar has been optimized automatically for generation (Minnen et al, 1996): The right-hand sides of the rules are reordered such that a simple left-to-right evaluation order constitutes the optimal evaluation order. With this grammar a simple top-down generation strategy does not terminate as a result of the head recursion in rule 3.…”

“…The problem arises as a result of the fact that these solutions lead to identical filters for the evaluation of the cat 3 literal, i.e., the solutions to cat 2 do not uniquely determine cat 3. optimization of the rules in the grammar is important. Through reordering the right-hand sides of the rules in the grammar the amount of nondeterminism can be drastically reduced as shown in Minnen et al (1996). This way of following the intended semantic dependencies the dependency constraint is satisfied automatically for a large class of grammars.…”

“…Unfolding can be used to eliminate superfluous filtering steps. Given an off-line optimization of the order in which the right-hand side categories in the rules of a logic grammar are processed (Minnen et al, 1996) the resulting processing behavior can be considered a generalization of the head corner generation approach (Shieber et al, 1990): Without the need to rely on notions such as semantic head and chain rule, a head corner behavior can be mimicked in a strict bottom-up fashion.…”

Off-line optimization for Earley-style HPSG processing

“…It is based on the notion of essential arguments, arguments which must be instantiated to ensure the efficient and terminating execution of a node. Minnen et al (1995) observe that the eaa is computationally infeasible, because it demands the investigation of almost all possible permutations of a grammar. Moreover, the interchanging of arguments in recursive proce-dures as proposed by Strzalkowski fails to guarantee that input and output grammars are semantically equivalent.…”

“…Moreover, the interchanging of arguments in recursive procedures as proposed by Strzalkowski fails to guarantee that input and output grammars are semantically equivalent. The Direct Inversion Approach (DI,~) of Minnen et al (1995) overcomes these problems by making the reordering process more goal-directed and developing a reformulation technique that allows the successful treatment of rules which exhibit head-recursion. Both the EAA and the DIA were presented as approaches to the inversion of parseroriented grammars into grammars suitable for generation.…”