3,149,619 research outputs found
An Abstract Morimoto Theorem for Generalized -structures
We abstract Morimoto's construction of complex structures on product
manifolds to pairs of certain generalized -structures on manifolds that are
not necessarily global products. As applications we characterize invariant
generalized complex structures on product manifolds in which one factor is a
Lie group and we generalize a theorem of Blair, Ludden and Yano on Hermitian
bicontact manifolds.Comment: 26 page
Abstract structures for moods in Greek
It is my intention to make two major points in this paper: 1. The first has to do with finding a frame within which the modal expressions of one particular Ancient IE [Indoeuropean] language – I have chosen Classical Greek – can be best described. I shall try to point out that the regularities which we find in these expressions must depend on an underlying principle, represented by abstract structures. These structures are semanto-syntactic, which means that the semantic properties or bundles of properties are arranged not in a linear order but in a hierarchical order, analogous to a bracketing in a PS structure. The abstract structures we propose have, of course, a very tentative character. They can only be accepted as far as evidence for them can be furnished. 2. My second point has to do with the modal verb forms that were the object of the studies of most Indo-Europeanists. If in the innermost bracket of a semanto-syntactic structure two semantic properties or bundles of properties can be exchanged without any further change in the total structure, and if this change is correlated with a change in verbal mood forms and nothing else, then I think we are faced with a case where these forms can be said to have a meaning of their own. I shall also try to show how these meanings are to be understood as bundles of features rather than as unanalyzed terms. In my final remarks: I shall try to outline the bearing these views have on comparative IE linguistics
Rewriting Abstract Structures: Materialization Explained Categorically
The paper develops an abstract (over-approximating) semantics for
double-pushout rewriting of graphs and graph-like objects. The focus is on the
so-called materialization of left-hand sides from abstract graphs, a central
concept in previous work. The first contribution is an accessible, general
explanation of how materializations arise from universal properties and
categorical constructions, in particular partial map classifiers, in a topos.
Second, we introduce an extension by enriching objects with annotations and
give a precise characterization of strongest post-conditions, which are
effectively computable under certain assumptions
Construction of Negatively Curved Cubic Carbon Crystals via Standard Realizations
We constructed physically stable sp2 negatively curved cubic carbon
structures which reticulate a Schwarz P-like surface. The method for
constructing such crystal structures is based on the notion of the standard
realization of abstract crystal lattices. In this paper, we expound on the
mathematical method to construct such crystal structures
Generalized Strong Preservation by Abstract Interpretation
Standard abstract model checking relies on abstract Kripke structures which
approximate concrete models by gluing together indistinguishable states, namely
by a partition of the concrete state space. Strong preservation for a
specification language L encodes the equivalence of concrete and abstract model
checking of formulas in L. We show how abstract interpretation can be used to
design abstract models that are more general than abstract Kripke structures.
Accordingly, strong preservation is generalized to abstract
interpretation-based models and precisely related to the concept of
completeness in abstract interpretation. The problem of minimally refining an
abstract model in order to make it strongly preserving for some language L can
be formulated as a minimal domain refinement in abstract interpretation in
order to get completeness w.r.t. the logical/temporal operators of L. It turns
out that this refined strongly preserving abstract model always exists and can
be characterized as a greatest fixed point. As a consequence, some well-known
behavioural equivalences, like bisimulation, simulation and stuttering, and
their corresponding partition refinement algorithms can be elegantly
characterized in abstract interpretation as completeness properties and
refinements
An exemplar model should be able to explain all syntactic priming phenomena : a commentary on Ambridge (2020)
The authors argue that Ambridge’s radical exemplar account of language cannot clearly explain all syntactic priming evidence, such as inverse preference effects (greater priming for less frequent structures), and the contrast between short-lived lexical boost and long-lived abstract priming. Moreover, without recourse to a level of abstract syntactic structure, Ambridge’s account cannot explain abstract priming in amnesia patients or cross-linguistic priming. Instead, the authors argue that abstract representations remain the more parsimonious account for the wide variety of syntactic priming phenomena
An Abstract Machine for Unification Grammars
This work describes the design and implementation of an abstract machine,
Amalia, for the linguistic formalism ALE, which is based on typed feature
structures. This formalism is one of the most widely accepted in computational
linguistics and has been used for designing grammars in various linguistic
theories, most notably HPSG. Amalia is composed of data structures and a set of
instructions, augmented by a compiler from the grammatical formalism to the
abstract instructions, and a (portable) interpreter of the abstract
instructions. The effect of each instruction is defined using a low-level
language that can be executed on ordinary hardware.
The advantages of the abstract machine approach are twofold. From a
theoretical point of view, the abstract machine gives a well-defined
operational semantics to the grammatical formalism. This ensures that grammars
specified using our system are endowed with well defined meaning. It enables,
for example, to formally verify the correctness of a compiler for HPSG, given
an independent definition. From a practical point of view, Amalia is the first
system that employs a direct compilation scheme for unification grammars that
are based on typed feature structures. The use of amalia results in a much
improved performance over existing systems.
In order to test the machine on a realistic application, we have developed a
small-scale, HPSG-based grammar for a fragment of the Hebrew language, using
Amalia as the development platform. This is the first application of HPSG to a
Semitic language.Comment: Doctoral Thesis, 96 pages, many postscript figures, uses pstricks,
pst-node, psfig, fullname and a macros fil
- …
