tailieunhanh - Báo cáo khoa học: "The Relationship Between Tree Adjoining Grammars "

We examine the relationship between the two grammatical formalisms: Tree Adjoining Grammars and Head Grammars. We briefly investigate the weak equivalence of the two formalisms. We then turn to a discussion comparing the linguistic expressiveness of the two formalisms. | The Relationship Between Tree Adjoining Grammars And Head Grammars . Weir . Joshi Department of Computer and Information Science University of Pennsylvania Philadelphia PA 19104 Abstract We examine the relationship between the two grammatical formalisms Tree Adjoining Grammars and Head Grammars. We briefly investigate the weak equivalence of the two formalisms. We then turn to a discussion comparing the linguistic expressiveness of the two formalisms. 1 Introduction Recent work 9 3 has revealed a very close formal relationship between the grammatical formalisms of Tree Adjoining Grammars tag s and Head Grammars HG s . In this paper we examine whether they have the same power of linguistic description. TAG S were first introduced in 1975 by Joshi Levy and Takahashifl and investigated further in 2 4 8 . HG s were first introduced by Pollard 5 . tag s and HG s were introduced to capture certain structural properties of natural languages. These formalisms were developed independently and are notationally quite different tag s deal with a set of elementary trees composed by means of an operation called adjoining. HG s maintain the essential character of context-free string rewriting rules except for the fact that besides concatenation of strings string wrapping operations are permitted. Observations of similarities between properties of the two formalisms led US to study the formal relationship between these two formalisms and the results of this investigation are presented in detail in 9 3 . We will briefly describe the formal relationship established in 9 3 showing tag s to be equivalent to a variant of HG s. We argue that the relationship between HG s and this variant of HG s called Modified Head Grammars MHG s is very close. Having discussed the question of the weak equivalence of tag s and HG s we explore in Sections 4 and 5 what might be loosely described as their strong equivalence. Section 4 discusses consequences of the substantial .

TỪ KHÓA LIÊN QUAN
crossorigin="anonymous">
Đã phát hiện trình chặn quảng cáo AdBlock
Trang web này phụ thuộc vào doanh thu từ số lần hiển thị quảng cáo để tồn tại. Vui lòng tắt trình chặn quảng cáo của bạn hoặc tạm dừng tính năng chặn quảng cáo cho trang web này.