Unification Grammars and Off-Line Parsability

Unification grammars are known to be Turing-equivalent; given a grammar G and a word w, it is undecidable whether w L(G). In order to ensure decidability, several constraints on grammars, commonly known as off-line parsability (OLP), were suggested, such that the recognition problem is decidable for grammars which satisfy OLP. An open question is whether it is decidable if a given grammar satisfies OLP. In this paper we investigate various definitions of OLP and discuss their interrelations, proving that some of the OLP variants are indeed undecidable. We then present a novel, decidable OLP constraint which is more liberal than the existing decidable ones.     

High pressure ellipsometry: a novel method for measuring the optical properties and electronic structure of materials in diamond anvil cells

High pressure ellipsometry (HPE) method was developed for determining the index of refraction of opaque materials in a diamond anvil cell (DAC). A main difficulty in DAC-based HPE, namely, the pressure-induced birefringence developed in the diamond, was overcome enabling the extraction of the ellipsometric parameters of the sample. The method used was based on the fact that an unpolarized light is unaffected by a retarding optical element and thus reduces the number of unknown parameters in the problem. Because of technical difficulties in using unpolarized light, a linear combination of orthogonal polarizations was applied. In the experimental procedure, multiangle measurements of the ellipsometric parameter ψ are collected at each pressure and the data is fitted together with a measurement of the near normal reflectivity, in order to extract the complex index of refraction. As a test case, this procedure was used to measure the high pressure index of refraction of iron up to 30 GPa for light with wavelengths of 532 and 633 nm. From the index of refraction as a function of pressure the diamond-iron interface emissivity for different pressures was derived and from which the phase transition α → ε could be identified and characterized. The emissivity increases with pressure both at the α (0-9 GPa) and the ε phase (21-30 GPa) however decreases at the mixed α - ε (9-21 GPa) range. From the imaginary part of the index of refraction the pressure dependence of the energy skin depth of iron was extracted. It was found that the energy skin depth increases by an order of magnitude at 30 GPa relative to ambient conditions.     

Data and models for metonymy resolution

We describe the first shared task for figurative language resolution, which was organised within SemEval-2007 and focused on metonymy. The paper motivates the linguistic principles of data sampling and annotation and shows the task’s feasibility via human agreement. The five participating systems mainly used supervised approaches exploiting a variety of features, of which grammatical relations proved to be the most useful. We compare the systems’ performance to automatic baselines as well as to a manually simulated approach based on selectional restriction violations, showing some limitations of this more traditional approach to metonymy recognition. The main problem supervised systems encountered is data sparseness, since metonymies in general tend to occur more rarely than literal uses. Also, within metonymies, the reading distribution is skewed towards a few frequent metonymy types. Future task developments should focus on addressing this issue.

Engineering performance in applied EPD: problems and solutions

Providing the particle size, shape and size distribution are suitable, appropriate dispersion media and surface-active additives can usually be found for the electrophoretic deposition (EPD) of powder with any chemical composition. The design of the EPD cell is largely dictated by the geometry of the final product and the required dimensional tolerances. The integrity of the microstructure and freedom of the product from process defects commonly depend on the deposition parameters and the dispersion chemistry.Demonstrations of laboratory feasibility for EPD products may prove straightforward, but developing an EPD process technology that is suitable for mass production can be far more challenging. This contribution reports four examples:

Efficient Set Operations in the Presence of Malicious Adversaries

We revisit the problem of constructing efficient secure two-party protocols for the problems of set intersection and set union, focusing on the model of malicious parties. Our main results are constant-round protocols that exhibit linear communication and a (practically) linear number of exponentiations with simulation-based security. At the heart of these constructions is a technique based on a combination of a perfectly hiding commitment and an oblivious pseudorandom function evaluation protocol. Our protocols readily transform into protocols that are UC secure, and we discuss how to perform these transformations.     

When are different type-logical semantic definitions defining equivalent meanings?

The paper considers the issue of different type-logical semantic definitions (of some natural language fragment) being “essentially” the same, though expressed using different type-systems. A definition of the equivalence is suggested, and is applied to four definitions of a very simple extensional fragment of English.     

Fabrication and performance of low loss optical components made byion exchange in glass

Passive optical components made by photolithography with ion exchange in glass have been developed. The technology used to fabricate these components is described, and their performance characterization is discussed. It is shown that this technique produces highly uniform low-loss devices     

A Proof-Theoretic Semantics for Adjectival Modification

The paper introduces a proof-theoretic semantics (PTS) for adjectival modification (adjective–noun combination) as an alternative to the traditional model-theoretic semantics basing meaning on truth-conditions. The paper considers the proof-theoretic meaning of modification by means of the three traditional adjective classes: intersective, subsective and privative. It does so by introducing a meaning-conferring natural-deduction proof system for such modification. The PTS theory of meaning is not polluted by ontological commitments, for example, a scale for beauty and a yardstick for being beautiful. It only uses syntactic artefacts of the proof language. The paper also defines, by suitable rules, iterated modification, shedding light on the relationship between iteration and adjectival classes. Modification via coordinated adjectives is covered too. An appendix delineates briefly the main ingredients of PTS.     

Fairness and the axioms of control predicates

Many recent axiomatic definitions for structured programming languages include control predicates,at(S), in(S), andafter(S), which are an abstraction of location counters. The usual axioms identify control locations so as to imply that no time (i.e., no state transition) is needed to pass from the end of one statement to the next, and in particular from the end of a loop body back to the test at the head of the loop. Here, an axiomatic framework for control predicates is examined. It is shown that if all the axioms are to be maintained with common representation mappings, there are difficult new requirements which need to be satisfied by an implementation for fair concurrent models of computation. Several approaches to resolving the difficulty are considered, and in particular it is suggested to replace some axioms of the formPQ byPeventually(Q), whereP andQ are control predicates, thereby separating control states previously identified.The North has receded, but the South has not yet arrived.-Reuven Miran, 42 Degrees in the Shade Every three lines intersect at a point, if the point is thick enough.-Folk theoremNote: A talk based on this paper was presented at the Colloquium on Temporal Logic and Specification, Altrincham, Cheshire, April 1987.C.R. Categories: D.3.1 [Programming languages] Formal definitions and theory: semantics; D..3.3 [Programming languages] Language constructs: control structures; F.3.1. [Logics and meanings of programs] Specifying and verifying and reasoning about programs.