Using general iteraction lemmata for languages defined by rational, linear, and algebraic sys-tems of equations on w-complete semirings, it can be shown that such iteration lemmata hold for certain classes of word and trace languages, and for process algebra classes related to them. The basic operation has to be associative with a neutral element, and is extended to sets of elements, such that the structure defined by it together with union and 0 is an w-complete semiring. With this property rational, linear and algebraic systems of equations can be de-fined, having a unique minimal solution as least fixed points. To guarantee iteration lemmata for the corresponding rational, linear and algebraic classes, a norm on the structure has to exit, fulfilling some monotonicity on union and extended opera-tion on sets. This article is an extended version of the paper presented at the workshop CS&P'98 in Berlin, September 28-30, 1998.
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It is demonstrated that the introduction of probability into Petri nets increases their power, in particular for their reachability sets. To achieve this the definition of accepted languages by probabilistic finite automata or probabilistic Turing machines with complexity restriction has to be modified.
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The concept of semilinear sets is generalized to commutative semirings. It is shown that the semilinear sets over commutative semirings are exactly the algebraic/rational sets over such structures.
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Between modal logic and closure operators for topological spaces as well as for formal languages there exists a strong relation. Modal logic allows to define classes of formal languages in several ways.
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It is shown that there don't exist quantum vector addition systems on various underlying structures for every number of productions. However, if the underlying vector space is restricted, such quantum vector addition systems exist.
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A generalization of contextual grammars by adding probabilities is introduced, enriching the generative power of such grammars. An example exhibits a non-contextual, even not context-free language.
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We present structural properties of languages constructed with catenation and shuffle, comprising iteration lemmata and closure properties of the language classes, as well as decidability results that follow.
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In this paper we define a certain class of process languages viewing processes as bi-partite graphs with an associative operation (sequential composition) on them. They describe finite evolutions of Petri nets. When extended to sets, we get an w-complete semiring such that rational, linear, and algebraic sets of such processes can be defined as least fixed points of systems of equations. With a norm of processes also iteration lemmata can be obtained. Finally, we also present a related structure of directed acyclic graphs.
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In this contribution we study an extension of zero-safe nets that allows to model cooperation scenarios. Since zero-safe nets cannot be represented as finite nets in general, we study an extension of the firing rule having a close connection to blind counter automatons and the theory of semi-flows. As a main result we obtain, that a representation can always be given as a finite P/T net - although our firing rule is an extension of the original one - i.e. it preserves all the events that have been allowed before.
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The definition of process admitted here follows the line developed for elementary (1-safe) Petri nets and published in [Cza 99], [Cza 2000a], [Cza-Kud 2000]. It pertains not to any particular net, thus allows for collecting processes into arbitrary sets, i.e. process languages, and for asking questions like: for a given process language decide if there exists a Place/Transition net and if yes, contruct it (synthesis). The collection of all process languages is a semantic domain for Place/Transition nets. w-process languages contain both finite and infinite processes. The main problems pursued are analysis, synthesis and iteration lemmata for w-process languages. Surprisingly, the problems enjoy much simpler solutions for processes generated by P/T nets than generated by elementary nets.
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Multiset languages are languages defined by multiset grammars in the sense of [4]. We extend to multiset languages the usual operations defined for string languages and define new operations specific for multiset languages. The closure properties of the main classes of multiset languages are investigated. Along these lines we introduce two notions of abstract family of multiset languages.
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We extend the investigation of synthesis and analysis of net structures and transition graphs to such with inhibitor relations, and show that the results obtained for the simpler case can be extended, too.
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We show that the results on analysis of net structures and transition graphs exhibited in [1] can be apllied also to generalized work flow net structures and related transition graphs.
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We investigate relations between transition graphs and net structures. Whereas for a given net structure there always exists a reachability graph, the inverse problem to find a net structure for a given transition graph is not solvable in general. We present sufficient and necessary conditions for several classes of transition graphs such as general, pseudo-bounded, bounded and elementary transition graphs, corresponding to general and (pseudo-)bounded P/T nets or C/E nets. We also give maximal and minimal solutions within an algebraic structure of net structures. The entire investigation is formulated in the framework of multiset theory.
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The present paper continues work from [7]. One goal of this work is to find a class of (object) Petri nets of lesser power than Turing machines, such that there exists a universal Petri net within that class. Another goal is to surpass the restricted synchronisation of transitions in object and system nets in the case of value semantics. Finally, an encoding of the proposed class of object Petri nets into linear logic Petri nets (LLPNs) is given, which directly leads to a specification that can be model-checked by existing tools.
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We present basic structures, definitions, normal forms, and a hierarchy of languages based on catenation, shuffle and their iterations, defined by algebraic closures or least fixed point solutions to systems of equations.
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We consider operations between languages, based on splitting the underlying alphabet into two disjoint sets, one of them having some priority. Such operations are generalizations of the classical catenation or shuffle operation, with which rational, linear and algebraic languages can be defined similar to the classical case. The basic properties of the corresponding language families are investigated too.
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This paper presents results regarding the various relations among the language classes defined by Concurrent Finite Automata, relations to other language classes, as well as decidability and closure properties.
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W pracy przedstawiono oddziaływanie związków chemicznych, w tym ubocznych produktów dezynfekcji (DBP) występujących w wodach basenowych na wybrane organizmy wskaźnikowe. Ocenę toksykologiczną poprzedzono krótką analizą podstawowych parametrów fizykochemicznych. Wykonane biotesty obejmowały zróżnicowaną grupę organizmów, tj. bakterie Aliivibrio fischeri, skorupiaki Daphnia magna, larwy owadów Chaoborus fahicans oraz rośliny naczyniowe Lemna minor. Analizowano korelację pomiędzy wynikami testów, co w przyszłości umożliwi wybór organizmów wskaźnikowych przydatnych w ocenie jakości wód basenowych.
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The study presents the impact of chemical substances present in swimming pool water, including disinfection by-products (DBP), on selected indicator organisms. Toxicological assessment was preceded by brief analysis of basic physicochemical parameters. The performed biotests involved a varied group of organisms, including bacteria (Aliivibrio fischeri), crustaceans (Daphnia magna), insect larvae (Chaoborus falvicans), and vascular plants (Lemna minor). Consideration was given to correlations between the results of the tests that will facilitate future selection of indicator organisms to be used in the assessment of quality of swimming pool waters.
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