We describe and evaluate the performance of a parallel search engine that is able to cope efficiently with concurrent read/write operations. Read operations come in the usual form of queries submitted to the search engine and write ones come in the form of new documents added to the text collection in an on-line manner, namely the insertions are embedded into the main stream of user queries in ...

In [6] it was shown that shuffle languages are contained in one-way-NSPACE(log n) and in P. In this paper we show that nondeterministic one-way logarithmic space is in some sense the lower bound for accepting shuffle languages. Namely, we show that there exists a shuffle language which is not accepted by any deterministic one-way Turing machine with space bounded by a sublinear function, and th...

Existing institutions do not seem well-designed to address paradigmatically global, intergenerational and ecological problems, such as climate change. 1 In particular, they tend to crowd out intergenerational concern, and thereby facilitate a “tyranny of the contemporary” in which successive generations exploit the future to their own advantage in morally indefensible ways (albeit perhaps unint...

Proponents of “truth-value glut” responses to the paradoxes of selfreference, such as Priest [7, 8] argue that “truth-value gap” analyses of the paradoxes fall foul of the strengthened liar paradox: “this sentence is not true.” If we pay attention to the role of assertion and denial and the behaviour of negation in both “gap” and “glut” analyses, we see that the situation with these approaches ...

As images are commonly transmitted or stored in compressed form such as JPEG lossy compression, image authentication demands techniques that can distinguish incidental modifications (e.g., compression) from malicious ones. In this paper, we propose an effective technique for image authentication which can prevent malicious manipulations but allow JPEG compression. An image is divided into block...

In this paper we present algorithms for jointly scheduling periodic tasks and hard aperiodic tasks with precedence relations in a distributed systems under the earliest deadline first algorithm. The periodic distributed processes are assumed to be guaranteed off-line and decomposed into a set of independent tasks by means of release time and deadline modifications. This paper proposes a similar...

Enforcing ontologies as conceptualisation standards in distributed architectures has some important drawbacks. It is, for instance, no solution for the legacy problem. In this article we address the possibility of accepting multiple heterogeneous ontologies in a distributed architecture. After discussing alternative ways to relate several ontologies we look into one particular (hierarchical) co...

Inoue et al. introduced an automaton on a twodimensional tape, which decides acceptance or rejection of an input tape by scanning the tape from various sides by various automata which move one way, and investigated the accepting power of such an automaton. This paper continues the investigation of this type of automata, especially, ∨-type automata (obtained by combining four three-way two-dimen...

Probabilistic ω-automata are variants of nondeterministic automata for infinite words where all choices are resolved by probabilistic distributions. Acceptance of an infinite input word can be defined in different ways: by requiring that (i) the probability for the accepting runs is positive (probable semantics), or (ii) almost all runs are accepting (almost-sure semantics), or (iii) the probab...