Unique Parallel Decomposition for the Pi-calculus

A (fragment of a) process algebra satisfies unique parallel decomposition if the definable behaviours admit a unique decomposition into indecomposable parallel components. In this paper we prove that finite processes of the pi-calculus, i.e. processes that perform no infinite executions, satisfy this property modulo strong bisimilarity and weak bisimilarity. Our results are obtained by an application of a general technique for establishing unique parallel decomposition using decomposition orders.Comment: In Proceedings EXPRESS/SOS 2016, arXiv:1608.0269

SOS rule formats for convex and abstract probabilistic bisimulations

Probabilistic transition system specifications (PTSSs) in the $nt \mu f\theta / nt\mu x\theta$ format provide structural operational semantics for Segala-type systems that exhibit both probabilistic and nondeterministic behavior and guarantee that bisimilarity is a congruence for all operator defined in such format. Starting from the $nt \mu f\theta / nt\mu x\theta$ format, we obtain restricted formats that guarantee that three coarser bisimulation equivalences are congruences. We focus on (i) Segala's variant of bisimulation that considers combined transitions, which we call here "convex bisimulation"; (ii) the bisimulation equivalence resulting from considering Park & Milner's bisimulation on the usual stripped probabilistic transition system (translated into a labelled transition system), which we call here "probability obliterated bisimulation"; and (iii) a "probability abstracted bisimulation", which, like bisimulation, preserves the structure of the distributions but instead, it ignores the probability values. In addition, we compare these bisimulation equivalences and provide a logic characterization for each of them.Comment: In Proceedings EXPRESS/SOS 2015, arXiv:1508.0634

Bisimilarity of Open Terms in Stream GSOS

Stream GSOS is a specification format for operations and calculi on infinite sequences. The notion of bisimilarity provides a canonical proof technique for equivalence of closed terms in such specifications. In this paper, we focus on open terms, which may contain variables, and which are equivalent whenever they denote the same stream for every possible instantiation of the variables. Our main contribution is to capture equivalence of open terms as bisimilarity on certain Mealy machines, providing a concrete proof technique. Moreover, we introduce an enhancement of this technique, called bisimulation up-to substitutions, and show how to combine it with other up-to techniques to obtain a powerful method for proving equivalence of open terms

Describing secure interfaces with interface automata

Interface automata are a model that allows for the representation of stateful interfaces. In this paper we introduce a variant of interface automata, which we call interface structure for security (ISS), that allows for the modelling of security. We focus on the property of non interference, more precisely in bisimulation-based non interference for reactive systems. We define the notion of compatible interfaces in this setting meaning that they can be composed so that a secure interface can be synthesized from the composition. In fact, we provide an algorithm that determines whether an ISS can be made secure by controlling (more specifically, pruning) some public input actions, and if so, synthesize the secure ISS. In addition, we also provide some sufficient conditions on the components ISS to ensure that their composition is secure (and hence no synthesis process is needed).Fil: Lee, Matias David. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; ArgentinaFil: D'argenio, Pedro Ruben. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentin

Logical Characterization of Bisimulation for Transition Relations over Probability Distributions with Internal Actions

In recent years the study of probabilistic transition systems has shifted to transition relations over distributions to allow for a smooth adaptation of the standard non-probabilistic apparatus. In this paper we study transition relations over probability distributions in a setting with internal actions. We provide new logics that characterize probabilistic strong, weak and branching bisimulation. Because these semantics may be considered too strong in the probabilistic context, Eisentraut et al. recently proposed weak distribution bisimulation. To show the flexibility of our approach based on the framework of van Glabbeek for the non-deterministic setting, we provide a novel logical characterization for the latter probabilistic equivalence as well

OncoLog Volume 48, Number 09, September 2003

Sentinel Lymph Node Biopsy: Detection of Micrometastases Leads to More Precise Staging of Breast and Melanoma Tumors Sentinel Lymph Node Biopsy Shows Promise in Eye and Colon Cancers New Research Promotes a More Dynamic View of Adult Stem Cell Differentiation: Hematopoietic Stem Cells May One Day Be Used to Repair Tissue Damage Caused by Radiation Therapy or Chemotherapy House Call: Understanding the Buzz over Stem Cells DiaLog: Directed Parathyroid Surgery, by Jeffrey E. Lee, MD, Professor, Department of Surgical Oncologyhttps://openworks.mdanderson.org/oncolog/1122/thumbnail.jp

Cornering New Physics in b --> s Transitions

We derive constraints on Wilson coefficients of dimension-six effective operators probing the b --> s transition, using recent improved measurements of the rare decays Bs --> mu+mu-, B --> K mu+mu- and B --> K* mu+mu- and including all relevant observables in inclusive and exclusive decays. We consider operators present in the SM as well as their chirality-flipped counterparts and scalar operators. We find good agreement with the SM expectations. Compared to the situation before winter 2012, we find significantly more stringent constraints on the chirality-flipped coefficients due to complementary constraints from B --> K mu+mu- and B --> K* mu+mu- and due to the LHCb measurement of the angular observable S_3 in the latter decay. We also list the full set of observables sensitive to new physics in the low recoil region of B --> K* mu+mu-.Comment: 18 pages, 6 figures, 4 tables. v3: typos correcte