SPPF (shared packed parse forest) is the best known graph representation of a parse forest (family of related parse trees) used in parsing with ambiguous/conjunctive grammars. Systematic general purpose transformations of SPPFs have never been investigated and are considered to be an open problem in software language engineering. In this paper, we motivate the necessity of having a transformati...

SPPF (shared packed parse forest) is the best known graph representation of a parse forest (family of related parse trees) used in parsing with ambiguous/conjunctive grammars. Systematic general purpose transformations of SPPFs have never been investigated and are considered to be an open problem in software language engineering. In this paper, we motivate the necessity of having a transformati...

The Foldy-Wouthuysen transformation (FWT) is used to separate distinct components of relativistic spinor field, e.g. electron and positron. Usually, the FWT is perturbative, but in some cases there is an involution operator and the transformation can be done exactly. We consider some aspects of an exact FWT and show that, even if the theory does not admit an involution operator, one can use the...

In the space H of quaternions, we investigate a natural, invariant geometry of the open, unit disc ∆H and of the open half-space H . These two domains are diffeomorphic via a Cayley-type transformation. We first study the geometrical structure of the groups of Möbius transformations of ∆H and H + and identify original ways of representing them in terms of two (isomorphic) groups of matrices wit...

For the integrable case of the discrete self-trapping (DST) model we construct a Bäcklund transformation. The dual Lax matrix and the corresponding dual Bäcklund transformation are also found and studied. The quantum analog of the Bäcklund transformation (Q-operator) is constructed as the trace of a monodromy matrix with an infinite-dimensional auxiliary space. We present the Q-operator as an e...

In a teleparallel theory of (2+1)-dimensional gravity developed in a previous paper, we examine generators of internal Lorentz transformations and of general affine coordinate transformations for static circularly symmetric exact solutions of gravitational field equation. The “spin” angular momentum, the energy-momentum and the “extended orbital angular momentum” are explicitly given for each s...

In Model-Driven Engineering, a software development process is a sequence of manipulation tasks that are applied to models, where model transformations play a relevant role. MOMENT (MOdel manageMENT) is a framework that is integrated in the Eclipse platform. MOMENT provides a collection of generic set-oriented operators to manipulate EMF models. In this paper, we present the model transformatio...

An example is given of a linear transformation which defines a wellbounded operator on LP[O, 1 J for 1 :::; p:::; oo. It is shown that the properties of the decomposition of the identity associated with this operator (and consequently the type of functional calculus that the operator admits) vary markedly depending on the domain space.

We construct the BRST operator for the non-linear WB2 and W4 algebras. Contrary to the general belief, the nilpotent condition of the BRST operator doesn’t determine all the coefficients. We find a three and seven parameter family of nilpotent BRST operator for WB2 and W4 respectively. These free parameters are related to the canonical transformation of the ghost antighost fields.