6,186 research outputs found
Reliable scientific service compositions
Abstract. Distributed service oriented architectures (SOAs) are increas-ingly used by users, who are insufficiently skilled in the art of distributed system programming. A good example are computational scientists who build large-scale distributed systems using service-oriented Grid comput-ing infrastructures. Computational scientists use these infrastructure to build scientific applications, which are composed from basic Web ser-vices into larger orchestrations using workflow languages, such as the Business Process Execution Language. For these users reliability of the infrastructure is of significant importance and that has to be provided in the presence of hardware or operational failures. The primitives avail-able to achieve such reliability currently leave much to be desired by users who do not necessarily have a strong education in distributed sys-tem construction. We characterise scientific service compositions and the environment they operate in by introducing the notion of global scien-tific BPEL workflows. We outline the threats to the reliability of such workflows and discuss the limited support that available specifications and mechanisms provide to achieve reliability. Furthermore, we propose a line of research to address the identified issues by investigating auto-nomic mechanisms that assist computational scientists in building, exe-cuting and maintaining reliable workflows.
Tensor products of maximal abelian subalgebras of C*-algebras
It is shown that if and are maximal abelian self-adjoint
subalgebras (masas) of C*-algebras and , respectively, then the
completion of the algebraic tensor product of
and in any C*-tensor product is maximal
abelian provided that has the extension property of Kadison and Singer
and contains an approximate identity for . An example is given to
show that can fail to be a masa in
with and unital if neither nor has the extension
property. This gives an answer to a long-standing question, but leaves open
some other interesting problems, one of which turns out to have a potentially
intriguing implication for the Kadison-Singer extension problem.Comment: 10 pages. Revision 1. Simplifications in the examples in section 3,
original first paragraph of section 4 delete
The order of the automorphism group of a binary -analog of the Fano plane is at most two
It is shown that the automorphism group of a binary -analog of the Fano
plane is either trivial or of order .Comment: 10 page
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