The formal power of one-visit attribute grammars

An attribute grammar is one-visit if the attributes can be evaluated by walking through the derivation tree in such a way that each subtree is visited at most once. One-visit (1V) attribute grammars are compared with one-pass left-to-right (L) attribute grammars and with attribute grammars having only one synthesized attribute (1S).\ud \ud Every 1S attribute grammar can be made one-visit. One-visit attribute grammars are simply permutations of L attribute grammars; thus the classes of output sets of 1V and L attribute grammars coincide, and similarly for 1S and L-1S attribute grammars. In case all attribute values are trees, the translation realized by a 1V attribute grammar is the composition of the translation realized by a 1S attribute grammar with a deterministic top-down tree transduction, and vice versa; thus, using a result of Duske e.a., the class of output languages of 1V (or L) attribute grammars is the image of the class of IO macro tree languages under all deterministic top-down tree transductions

Interpretation and reduction of attribute grammars

An attribute grammar (AG) is in reduced form if in all its derivation trees every attribute contributes to the translation. We prove that, eventhough AG are generally not in reduced form, they can be reduced, i.e., put into reduced form, without modifying their translations. This is shown first for noncircular AG and then for arbitrary AG. In both cases the reduction consists of easy (almost syntactic) transformations which do not change the semantic domain of the AG. These easy transformations are formalized by introducing the notion of AG interpretation as an extension to AG of the concept of context-free grammar form. Finally we prove that any general algorithm for reducing even the simple class of L-AG needs exponential time (in the size of the input AG) infinitely often

Structure and implications of the GLN

Thesis (S.M.)--Massachusetts Institute of Technology, School of Architecture and Planning, Program in Media Arts and Sciences, 2013.Cataloged from PDF version of thesis.Includes bibliographical references (p. 69-73).Languages vary enormously in global importance because of historical, demographic, political, and technological forces, and there has been much speculation about the current and future status of English as a global language. Yet there has been no rigorous way to define or quantify the relative global influence of languages. I propose that the structure of the network connecting multilingual speakers or translated texts, which I call the Global Language Network, provides a concept of language importance that is superior to simple economic or demographic measures. I map three independent global language networks (GLN) from millions of records of online and printed linguistic expressions taken from Wikipedia, Twitter, and UNESCO's database of book translations. I find that the structure of the three GLNs is hierarchically organized around English and a handful of hub languages, which include Spanish, German, French, Russian, Malay, and Portuguese, but not Chinese, Hindi or Arabic. Finally, I validate the measure of a language's centrality in the GLNs by showing that it correlates with measures of the number of illustrious people born in the countries associated with that language. I suggest that other phenomena of a language's present and future influence are systematically related to the structure of the global language networks.by Shahar Ronen.S.M

Simple multi-visit attribute grammars

An attribute grammar is simple multi-visit if each attribute of a nonterminal has a fixed visit-number associated with it such that, during attribute evaluation, the attributes of a node which have visit-number j are computed at the jth visit to the node. An attribute grammar is l-ordered if for each nonterminal a linear order of its attributes exists such that the attributes of a node can always be evaluated in that order (cf. the work of Kastens).\ud \ud An attribute grammar is simple multi-visit if and only if it is l-ordered. Every noncircular attribute grammar can be transformed into an equivalent simple multi-visit attribute grammar which uses the same semantic operations.\ud \ud For a given distribution of visit-numbers over the attributes, it can be decided in polynomial time whether the attributes can be evaluated according to these visit-numbers. The problem whether an attribute grammar is simple multi-visit is NP-complete

Proofs of partial correctness for attribute grammars with applications to recursive procedures and logic programming

AbstractAn extension of the inductive assertion method allowing one to prove the partial correctness of an attribute grammar w.r.t. a specification is presented. It is complete in an abstract sense. It is also shown that the semantics of systems of recursive imperative procedures or of recursive applicative procedures computed with call-by-value or call-by-name can be expressed by an attribute grammar associating attributes with the nodes of the so-called trees of calls. Hence the proof methods for the partial correctness of attribute grammars can be applied to these recursive procedures. We show also how the proof method can be applied in logic programming

Hybrid grammars for parsing of discontinuous phrase structures and non-projective dependency structures

We explore the concept of hybrid grammars, which formalize and generalize a range of existing frameworks for dealing with discontinuous syntactic structures. Covered are both discontinuous phrase structures and non-projective dependency structures. Technically, hybrid grammars are related to synchronous grammars, where one grammar component generates linear structures and another generates hierarchical structures. By coupling lexical elements of both components together, discontinuous structures result. Several types of hybrid grammars are characterized. We also discuss grammar induction from treebanks. The main advantage over existing frameworks is the ability of hybrid grammars to separate discontinuity of the desired structures from time complexity of parsing. This permits exploration of a large variety of parsing algorithms for discontinuous structures, with different properties. This is confirmed by the reported experimental results, which show a wide variety of running time, accuracy and frequency of parse failures.Publisher PDFPeer reviewe

Skin, Kin and Clan

Australia is unique in the world for its diverse and interlocking systems of Indigenous social organisation. On no other continent do we see such an array of complex and contrasting social arrangements, coordinated through a principle of ‘universal kinship’ whereby two strangers meeting for the first time can recognise one another as kin. For some time, Australian kinship studies suffered from poor theorisation and insufficient aggregation of data. The large-scale AustKin project sought to redress these problems through the careful compilation of kinship information. Arising from the project, this book presents recent original research by a range of authors in the field on the kinship and social category systems in Australia. A number of the contributions focus on reconstructing how these systems originated and developed over time. Others are concerned with the relationship between kinship and land, the semantics of kin terms and the dynamics of kin interactions