874 research outputs found
Labelled transition systems as a Stone space
A fully abstract and universal domain model for modal transition systems and
refinement is shown to be a maximal-points space model for the bisimulation
quotient of labelled transition systems over a finite set of events. In this
domain model we prove that this quotient is a Stone space whose compact,
zero-dimensional, and ultra-metrizable Hausdorff topology measures the degree
of bisimilarity such that image-finite labelled transition systems are dense.
Using this compactness we show that the set of labelled transition systems that
refine a modal transition system, its ''set of implementations'', is compact
and derive a compactness theorem for Hennessy-Milner logic on such
implementation sets. These results extend to systems that also have partially
specified state propositions, unify existing denotational, operational, and
metric semantics on partial processes, render robust consistency measures for
modal transition systems, and yield an abstract interpretation of compact sets
of labelled transition systems as Scott-closed sets of modal transition
systems.Comment: Changes since v2: Metadata updat
Organic charge-transfer phase formation in thin films of the BEDT-TTF/TCNQ donor-acceptor system
We have performed charge transfer phase formation studies on the
donor/acceptor system
bis(ethylendithio)tetrathiafulvalene,(BEDT-TTF)/tetracyanoquinodimethane,(TCNQ)
by means of physical vapor deposition. We prepared donor/acceptor bilayer
structures on glass and Si(100)/SiO_2 substrates held at room temperature and
analyzed the layer structures by optical microscopy, X-ray diffraction and
focused ion beam cross sectioning before and after annealing. We found clear
evidence for the formation of a charge transfer phase during the annealing
procedure. For the as-grown samples we could not detect the occurrence of a
charge transfer phase. X-ray diffraction indicated that the monoclinic variant
of the (BEDT-TTF)-TCNQ was formed. This was further corroborated by
single-source evaporation experiments from pre-reacted (BEDT-TTF)-TCNQ obtained
from solution growth, and in particular from co-evaporation experiments of
(BEDT-TTF)-TCNQ and TCNQ. In the course of these experiments we found that
(0,l,l)-oriented BEDT-TTF layers can be prepared on alpha-Al_2O_3 (1,1,-2,0)
substrates at about 100 C using (BEDT-TTF)-TCNQ as source material. We
speculate that due to its high vapor pressure the TCNQ component serves as a
carrier gas for BEDT-TTF vapor phase transport.Comment: 14 pages, 8 figures. Added new author, new section about
co-evaporation technique, new references, new figure
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