论文标题

Hypergraph Lambek演算

Hypergraph Lambek Calculus

论文作者

Pshenitsyn, Tikhon

论文摘要

众所周知,无上下文的语法可以扩展到产生图形语法的图形。这样的基本方法之一是超越替代语法。另一方面,有类型的语法也可以描述弦语。在本文中,我们研究了如何将基于lambek cyculus($ \ mathrm {l} $)和基于语法扩展到图形。结果方法称为HyperGraph Lambek cyculus($ \ mathrm {hl} $)。它是逻辑上的顺序演算,其序列是图形。它自然会扩展Lambek微积分,并且还允许一个人嵌入其变体(交换$ \ Mathrm {l} $,$ \ Mathrm {NL \ Diamondsuit} $,$ \ Mathrm {l} _ {\ Mathbf {\ Mathbf {1}}}}}}^\ ast $)。此外,Lambek微积分的许多属性(剪切消除,计数器,模型)可以提升为$ \ Mathrm {hl} $。但是,尽管Lambek语法在弦乐器案例中等同于无上下文语法,但HyperGraph Lambek语法比HyperEdge替换语法强大得多。特别是,前者可以在没有隔离节点的情况下生成所有图的语言。所有双方图的语言; Hyperde替换语法产生的语言的有限交集。然而,$ \ mathrm {hl} $中的衍生性问题以及基于$ \ mathrm {hl} $的语法成员资格问题是NP完整的,以及HyperEdge替换语法的成员资格问题。

It is known that context-free grammars can be extended to generating graphs resulting in graph grammars; one of such fundamental approaches is hyperedge replacement grammars. On the other hand there are type-logical grammars which also serve to describe string languages. In this paper, we investigate how to extend the Lambek calculus ($\mathrm{L}$) and grammars based on it to graphs. The resulting approach is called hypergraph Lambek calculus ($\mathrm{HL}$). It is a logical sequential calculus whose sequents are graphs; it naturally extends the Lambek calculus and also allows one to embed its variants (commutative $\mathrm{L}$, $\mathrm{NL\diamondsuit}$, $\mathrm{L}_{\mathbf{1}}^\ast$). Besides, many properties of the Lambek calculus (cut elimination, counters, models) can be lifted to $\mathrm{HL}$. However, while Lambek grammars are equivalent to context-free grammars in the string case, hypergraph Lambek grammars are much more powerful than hyperedge replacement grammars. Particularly, the former can generate the language of all graphs without isolated nodes; the language of all bipartite graphs; finite intersections of languages generated by hyperedge replacement grammars. Nevertheless, the derivability problem in $\mathrm{HL}$ and the membership problem for grammars based on $\mathrm{HL}$ are NP-complete as well as the membership problem for hyperedge replacement grammars.

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