CCS with Hennessy's merge has no finite-equational axiomatization

Abstract This paper confirms a conjecture of Bergstra and Klop¿s from 1984 by establishing that the process algebra obtained by adding an auxiliary operator proposed by Hennessy in 1981 to the recursion free fragment of Milner¿s Calculus of Communicationg Systems is not finitely based modulo bisimulation equivalence. Thus Hennessy¿s merge cannot replace the left merge and communication merge operators proposed by Bergstra and Klop, at least if a finite axiomatization of parallel composition is desired. 2000 MATHEMATICS SUBJECT CLASSIFICATION: 08A70, 03B45, 03C05, 68Q10, 68Q45, 68Q55, 68Q70. CR SUBJECT CLASSIFICATION (1991): D.3.1, F.1.1, F.1.2, F.3.2, F.3.4, F.4.1. KEYWORDS AND PHRASES: Concurrency, process algebra, CCS, bisimulation, Hennessy¿s merge, left merge, communication merge, parallel composition, equational logic, complete axiomatizations, non-finitely based algebras

Acta Informatica manuscript No. (will be inserted by the editor) A Complete Classification of the Expressiveness of Interval Logics of Allen’s Relations The General and the Dense Cases

Abstract Interval temporal logics take time intervals, instead of time instants, as their primitive temporal entities. One of the most studied interval temporal logics is Halpern and Shoham’s modal logic of time intervals HS, which associates a modal operator with each binary relation between intervals over a linear order (the so-called Allen’s interval relations). In this paper, we compare and classify the expressiveness of all fragments of HS on the class of all linear orders and on the subclass of all dense linear orders. For each of these classes, we identify a complete set of definabilities between HS modalities, valid in that class, thus obtaining a complete classification of the family of all 4096 fragments of HS with respect to their expressiveness. We show that on the class of all linear orders there are exactly 1347 expressively different fragments of HS, while on the class of dense linear orders there are exactly 966 such expressively different fragments

LNCS

In the analysis of reactive systems a quantitative objective assigns a real value to every trace of the system. The value decision problem for a quantitative objective requires a trace whose value is at least a given threshold, and the exact value decision problem requires a trace whose value is exactly the threshold. We compare the computational complexity of the value and exact value decision problems for classical quantitative objectives, such as sum, discounted sum, energy, and mean-payoff for two standard models of reactive systems, namely, graphs and graph games

Late and Early Semantics Coincide for Testing

AbstractLate and early operational semantics are given for CCS. Late and early testing are defined and it is shown that the derived preorders coincide, contrary to what happens for bisimulation-like equivalences

Greining ginsenosíð sambanda í gingseng afurðum

Neðst á síðunni er hægt að nálgast greinina í heild sinni með því að smella á hlekkinn Skoða/Opna(view/open)An evaluation of ginseng products on the Icelandic market is described. Ginsenosides were quantitatively determined by HPLC, with concomitant qualtitative analysis by TLC. Results showed substantial variation between different products, both with regard to the content of individual ginsenosides and the total ginsenoside concentration. Recommended daily dosages vary between manufacturers. Results showed that intake of the manufacturers' recommended adult daily dosages would result in daily consumption of total ginsenosides ranging from practically none at all to 55 mg. Results of the study emphasize the need for more stringent and efficient control of herbal remedies.Háþrýstivökvagreining (HPLC) var notuð til að greina ginsenosíð sambönd í ginseng afurðum sem seldar eru hér á landi. Niðurstöður sýna að ginsenosíð innihald er mjög mismikið í þeim afurðum sem rannsóknin tók til, bæði hvað varðar heildarstyrk ginsenosíða og innbyrðis hlutfall þeirra. Ráðleggingar framleiðenda um skammtastærðir eru afar breytilegar og niðurstöður sýndu að heildarmagn ginsenosíð sambanda í dagskammti, samkvæmt tilmælum framleiðenda, er frá því að vera nánast ekkert og upp í 55 mg. Niðurstöður benda eindregið til að þörf sé fyrir strangara og virkara eftirlit með náttúruvöru

Greining ginsenosíð sambanda í gingseng afurðum

Neðst á síðunni er hægt að nálgast greinina í heild sinni með því að smella á hlekkinn Skoða/Opna(view/open)An evaluation of ginseng products on the Icelandic market is described. Ginsenosides were quantitatively determined by HPLC, with concomitant qualtitative analysis by TLC. Results showed substantial variation between different products, both with regard to the content of individual ginsenosides and the total ginsenoside concentration. Recommended daily dosages vary between manufacturers. Results showed that intake of the manufacturers' recommended adult daily dosages would result in daily consumption of total ginsenosides ranging from practically none at all to 55 mg. Results of the study emphasize the need for more stringent and efficient control of herbal remedies.Háþrýstivökvagreining (HPLC) var notuð til að greina ginsenosíð sambönd í ginseng afurðum sem seldar eru hér á landi. Niðurstöður sýna að ginsenosíð innihald er mjög mismikið í þeim afurðum sem rannsóknin tók til, bæði hvað varðar heildarstyrk ginsenosíða og innbyrðis hlutfall þeirra. Ráðleggingar framleiðenda um skammtastærðir eru afar breytilegar og niðurstöður sýndu að heildarmagn ginsenosíð sambanda í dagskammti, samkvæmt tilmælum framleiðenda, er frá því að vera nánast ekkert og upp í 55 mg. Niðurstöður benda eindregið til að þörf sé fyrir strangara og virkara eftirlit með náttúruvöru

A note on an expressiveness hierarchy for multi-exit iteration

Multi-exit iteration is a generalization of the standard binary Kleene star operation that allows for the specification of agents that, up to bisimulation equivalence, are solutions of systems of recursion equations of the formX_1 = P_1 X_2 + Q_1 X_n = P_n X_1 + Q_n where n is a positive integer, and the P_i and the Q_i are process terms. The addition of multi-exit iteration to Basic Process Algebra (BPA) yields a more expressive language than that obtained by augmenting BPA with the standard binary Kleene star. This note offers an expressiveness hierarchy, modulo bisimulation equivalence, for the family of multi-exit iteration operators proposed by Bergstra, Bethke and Ponse