We establish a 1-1 correspondence between Valiant’s character theory of matchgate/matchcircuit [14] and his signature theory of planar-matchgate/matchgrid [16], thus unifying the two theories in expressibility. In [5], we had established a complete characterization of general matchgates, in terms of a set of useful Grassmann-Plücker identities. With this correspondence, we give a corresponding ...

We exhibit a rst-order deenable picture language which we prove is not expressible by any star-free picture expression, i. e., it is not star-free. Thus rst-order logic over pictures is strictly more powerful than star-free picture expressions are. This is in sharp contrast with the situation with words: the well-known McNaughton-Papert theorem states that a word language is expressible by a rs...

Conceptual Programming is a term meant to convey a similar idea to that of Logic Programming, but at a higher level of representation. Programming with concepts, as presented here, has all the advantages that many knowledge representation schemes have in dealing with declarative knowledge i.e. explicitness, naturalness, expressibility, and transparency. It also gives procedural knowledge these ...

We revisit the notion of deep equality among objects in an ob ject database from a formal point of view We present three natural formalizations of deep equality one based on the in nite value trees associated with objects one based on the greatest xpoint of an oper ator on equivalence relations among objects and one based on indis tinguishability of objects using observations of atomic values r...

A new fully secure ciphertext-policy attributed based encryption (CP-ABE) scheme with high expressibity access policy is presented. Our CP-ABE scheme uses tree-based access structure which includes AND, OR, threshold and NOT gates which granted high degree of expressibility for encryptor to make an access policy. Moreover, our scheme achieves full security CP-ABE definition where any access str...

We consider fragments of first-order logic over finite words. In particular, we deal with first-order logic with a restricted number of variables and with the lower levels of the alternation hierarchy. We use the algebraic approach to show decidability of expressibility within these fragments. As a byproduct, we survey several characterizations of the respective fragments. We give complete proo...

We study whether, in the π-calculus, the match prefix—a conditional operator testing two names for (syntactic) equality—is expressible via the other operators. Previously, Carbone and Maffeis proved that matching is not expressible this way under rather strong requirements (preservation and reflection of observables). Later on, Gorla developed a by now widely-tested set of criteria for encoding...

We refine the constructions of Ferrante-Rackoff and Solovay on iterated definitions in first-order logic and their expressibility in with polynomial size formulas. These constructions introduce additional quantifiers; however, we show that these extra quantifiers range over only finite sets. We prove optimal upper and lower bounds on the quantifier complexity of polynomial size formulas obtaine...

A concurrent program generally comprises a collection of threads1 that interact cooperatively, either directly or through shared data objects. In the latter case the sharing needs to be implemented by some mechanism that ensures mutually exclusive access, or possibly “concurrent read / exclusive write”. Ada and the Real-Time Specification for Java have taken different approaches to mutual exclu...

Among Quine’s main concerns in his “On What There Is”, there was that of solving a problem of expressibility for ontological denials. His proposed solution to such a problem was, in a purely Carnapian vein, a shift of attention to the semantic features of ontological claims – what Quine called the strategy of “semantic ascent”. Quine’s relevant assumption is that talk about language is much les...