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1
Content available remote A Protocol of Mutual Exclusion for DSM Based on Vectors of Global Timestamps
Czaja L.
Fundamenta Informaticae
|
2018
|
Vol. 157, nr 4
359--370
EN
A new protocol using vectors of global timestamps for mutual exclusion in systems with Distributed Shared Memory (DSM) is described and some of its properties are proved.
2
Content available remote Remarks on Memory Consistency Description
Czaja L.
Fundamenta Informaticae
|
2016
|
Vol. 147, nr 2/3
209--221
EN
Two observations in the matter of pictorial as well as formal presentation of some consistency in distributed shared memory are made. The first concerns geometric transformation of line segments and points picturing read/write operations, the second - converting partial order of the operations into linear order of their initiations and terminations. This allows to reduce serialization of the read/write operations as a whole to permutations of their beginnings and ends. Some draft proposals are introduced.
3
Content available remote Self-Modifying Nets for Synchronous, Connection-Oriented, Multicast Communication
Czaja L.
Fundamenta Informaticae
|
2014
|
Vol. 129, nr 1/2
27--36
EN
Petri net structures are used as communication model of network systems where message transfer channels are represented by the nets' edges, communicating agents - by nets' places and actions of communication - by nets' transitions, which here are called transmissions. The role of (structured) tokens play send/receive statements, that arrive at random, which makes the distribution of edges change dynamically. In this sense a net is self-modyfying: although the set of agents-places is fixed, the channels and communicating actions vary in the course of the net activity. Problems of deadlock and fairness is investigated.
4
Content available remote Floating Channels Between Communicating Nets
Czaja L.
Fundamenta Informaticae
|
2014
|
Vol. 133, nr 2/3
123--132
EN
A network system is given as a set of Petri net-like structures called agents. Each agent has a singled out place interpreted as a communication port with ingoing edges labelled with send(p1, ..., pn) and receive(q1, ..., qm) commands, where pi, qj are names of ports of its interlocutors. Every such edge exits a transition emiting a request for send or receivemessage. A transmission channel between the agent and its intelocutors is established when its port holds a send or receive command, while ports of its interlocutors hold respective (matching) communication commands. This gives rise to communication between the agent and its interlocutors, after which the channel is disrupted: hence floating channels. Some behavioural properties of such network system are examined, their decision complexity, deadlock and fairness in their number.
5
Content available remote Rough Net Structures : Example of Information System
Czaja L.
Fundamenta Informaticae
|
2013
|
Vol. 127, nr 1-4
81--97
EN
Information system of net structures based on their calculus (a distributive lattice) is introduced and, in this context, basic notions of rough set theory are re-formulated and exemplified.
6
Content available remote Equations for Asynchronous Message Passing
Czaja L.
Fundamenta Informaticae
|
2013
|
Vol. 128, nr 1-2
35--45
7
Content available remote Exclusive Access to Resources in Distributed Shared Memory Architecture
Czaja L.
Fundamenta Informaticae
|
2012
|
Vol. 119, nr 3/4
265-280
EN
A protocol of mutual exclusion with FIFO discipline is devised for distributed systems with Distributed Shared Memory (DSM) and without any central server. To this end, replication of data - a principal feature of DSM is exploited. Some data consistency is discussed.
8
Content available remote On Synthesis and Analysis of Generalized Work Flow Net Structures and Transition Graphs
Czaja L., Kudlek M.
Fundamenta Informaticae
|
2011
|
Vol. 112, nr 1
39-45
EN
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.
9
Content available remote On Deadlock and Fairness Decision Problems for Computations on Client-server Systems
Czaja L.
Fundamenta Informaticae
|
2011
|
Vol. 109, nr 3
255-264
EN
Phenomena that inherently happen in distributed computing - some types of deadlock and fairness or starvation - are examined in a client-server model. Messages travelling between clients and a server are: request for an action, permission to start it, and termination of its execution. Deadlock-prone and (un)fair behaviours are formulated for the model and equivalence of the respective formulae to formulae expressing emptiness and finiteness of some sets generated by the model is established. From these results, some answers to decision problems for the aforesaid properties are obtained. Furthermore, equivalence between the so-called strong fairness (specified by first-order formula) and weak-fairness (second-order formula) is demonstrated
10
Content available remote Synthesis and Analysis of Net Structures and Transition Graphs with Inhibitor Relations
Czaja L., Kudlek M.
Fundamenta Informaticae
|
2010
|
Vol. 101, nr 1/2
1-7
EN
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.
11
Content available remote Analysis and Synthesis of Net Structures and Transition Graphs
Czaja L., Kudlek M.
Fundamenta Informaticae
|
2009
|
Vol. 93, nr 1-3
97-110
EN
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.
12
Content available remote Boolean Algebra of Nets, their Synthesis and Analysis
Czaja L.
Fundamenta Informaticae
|
2008
|
Vol. 85, nr 1-4
89-95
13
Content available remote Interpreted Nets
Czaja L.
Fundamenta Informaticae
|
2007
|
Vol. 79, nr 3-4
283-293
EN
The nets considered here are an extension of Petri nets in two aspects. In the semantic aspect, there is no one firing rule common to all transitions, but every transition is treated as an operator on data stored in its entry places and return results in its exit places. A state (marking) is a mapping of places (variables) into a given data structure, while interpretation is a mapping of transitions into a set of state transformers. Locality of transition's activity is like in Petri nets. In the structural aspect, entry and exit places to a transition are ordered. A concatenation of such nets is defined, hence their calculus (a monoid). This allows for combining small nets into large ones, in particular designing a computation and control parts separately, then putting them together into one. Such extended nets may produce, in particular, other nets. A number of properties of the operation on nets and their decomposition are demonstrated.
14
Content available remote Equations for message passing
Czaja L.
Fundamenta Informaticae
|
2006
|
Vol. 72, nr 1-3
81-93
EN
A specification of systems based on message passing paradigm is proposed. To this end, an algebraic structure called a semiring of formal polynomials with restricted idempotency of multiplication is taken and fix-point equations specifying (parallel) systems are constructed. Their solution provides an i"mplementation" of the system, in particular, a Petri net of various kind. Moreover, it determines a global information on capability of sending or receiving a message by objects from a local information on their readiness to do this.
15
Content available remote An Axiomatic Framework for Proving Correctness of Nets
Czaja L.
Fundamenta Informaticae
|
2005
|
Vol. 67, nr 1-3
45--64
EN
A method of constructing net (cause-effect structure and Petri net) from a specification given as an axiomatic system and proving behaviour of the net to conform to the specification is presented and illustrated by two examples.
16
Content available remote Proving Nets Correct via Cause-Effect Structures (An Experiment)
Czaja L.
Fundamenta Informaticae
|
2003
|
Vol. 54, nr 2,3
165-183
EN
Proving safety and liveness of parallel systems is of unquestionable importance in system construction activity. A proof method for systems represented by nets (cause-effect structures and Petri nets) is proposed. Its outline is the following. (1) Let a problem specification as a formal theory i.e. a language system with specific relation symbols (operations, in particular), axioms and first-order inference rules be given. For each symbol introduce a class of atomic c-e structures (counterpart of Petri net transitions) to be the symbol's operational representative. (2) Using algebraic calculus of cause-effect structures, construct - from the atoms - a c-e structure and equivalent net intended to behave in accordance with the axioms (a mechanical step); (3) From the cause-effect structure just constructed, infer an algebraic structure and prove it to be a model (in terms of model theory) of the axiomatic system specifying the problem.
17
Content available remote Place/Transition Petri Net Evolutions: Recording Ways, Analysis and Synthesis
Czaja L.
Fundamenta Informaticae
|
2002
|
Vol. 51, nr 1,2
43-58
EN
Four semantic domains for Place/Transition Petri nets and their relationships are considered. They are monoids of respectively: firing sequences, processes, traces and dependence graphs. For each of them the analysis and synthesis problem is stated and solved. The monoid of processes is defined in a non-standard way. Nets under consideration involve weights of arrows and capacities (finite or infinite) of places. However, the analysis and synthesis tasks require nets to be pure, i.e. each of their transition must have the pre-set and post-set disjoint.
18
Content available remote w-Process Languages for Place/Transition Nets
Czaja L., Kudlek M.
Fundamenta Informaticae
|
2001
|
Vol. 47, nr 3,4
217-229
EN
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.
19
Content available remote Rational, Linear and algebraic process languages and iteration lemmata
Czaja L., Kudlek M.
Fundamenta Informaticae
|
2000
|
Vol. 43, Nr 1-4
49-60
EN
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.
20
Content available remote Representing hand-shake channel communication in the calculus of cause-effect structures
Czaja L.
Fundamenta Informaticae
|
1999
|
Vol. 37, Nr 4
343-368
EN
It is shown how control aspects of the CSP-like communication mechanism may be repre-sented as cause-effect structures, by using their calculus. A correctness proof of this transfor-mation, i.e. its preserving of behaviour, has been given. A CSP-like parallel combinatory for c-e structures is proposed as well as its semantic counterpart. Compositionality property is proved.
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