Conference Papers & Presentations (Computer Science)

Permanent URI for this collectionhttp://hdl.handle.net/2263/32438

Browse

Now showing 1 - 18 of 18

Aristotle's "Sea Battle" Scenario: a matter of Strict versus Lazy Evaluation
(2024-01-17) Gruner, Stefan
From Aristotle's "de Interpretatione IX" we are familiar with the famous scenario: "tomorrow there will be a sea battle, OR tomorrow there will be NO sea battle". From a purely syntactic-formal point of view, Aristotle's example sentence has the form S = (B v ~B) which ought to be tautologically true in Aristotle's own classical bi-valent logic which was based on the principle of "tertium non datur" (TND). For this specific example S, however, Aristotle abandoned his own TND principle as he was (unnecessarily) worried that a logical tautology of sentences with future contingencies in their material semantics would imply an ontological determinism in history. As an opponent of ontological-historic determinism, Aristotle thus decided to forbid the application of the TND principle in all sentences that materially express future contingencies. Formally, this corresponds to a strict interpretation of the trivalent Kleene Logic with its third truth value U, in which (B v ~B) with I(B)=U is no tautology. Philosophically, however, the questions arise: Are we anyhow "forced" to "follow" Aristotle in his decision to abandon the TND principle for future contingencies? Or do we have an alternative option to "rescue" the TND principle also for future contingency sentences - and, if yes, how? In this PSSA'24 talk it is argued that the TND principle can indeed be "reconciled" with future contingencies and Kleene's U if we admit as a valid method of formal reasoning the so-called "Lazy Evaluation" strategy for which we can find application examples both in classical Mathematics as well as modern Informatics (Computer Science). A full paper, in which the main argument of this talk shall be elaborated in further details, shall be forthcoming in due course.
Synthesis of cost-optimal multi-agent systems for resource allocation
(Open Publishing Association, 2022-09) Timm, Nils; Botha, Josua; nimm@cs.up.ac.za
Multi-agent systems for resource allocation (MRAs) have been introduced as a concept for modelling competitive resource allocation problems in distributed computing. An MRA is composed of a set of agents and a set of resources. Each agent has goals in terms of allocating certain resources. For MRAs it is typically of importance that they are designed in a way such that there exists a strategy that guarantees that all agents will achieve their goals. The corresponding model checking problem is to determine whether such a winning strategy exists or not, and the synthesis problem is to actually build the strategy. While winning strategies ensure that all goals will be achieved, following such strategies does not necessarily involve an optimal use of resources. In this paper, we present a technique that allows to synthesise cost-optimal solutions to distributed resource allocation problems. We consider a scenario where system components such as agents and resources involve costs. A multi-agent system shall be designed that is cost-minimal but still capable of accomplishing a given set of goals. Our approach synthesises a winning strategy that minimises the cumulative costs of the components that are required for achieving the goals. The technique is based on a propositional logic encoding and a reduction of the synthesis problem to the maximum satisfiability problem (Max-SAT). Hence, a Max-SAT solver can be used to perform the synthesis. From a truth assignment that maximises the number of satisfied clauses of the encoding a cost- optimal winning strategy as well as a cost-optimal system can be immediately derived.
Transfer learning in evolutionary spaces
(Association for Computing Machinery, 2022-07) Pillay, Nelishia; Pillay, Nelishia
No abstract available.
Back to BASIC in Compiler Construction
(College of Science, Engineering and Technology: University of South Africa (UNISA), 2019) Gruner, Stefan
This short-paper offers an experience report about a successful way of giving an introductory compiler construction course to 3rd-year undergraduate students. Because the in-depth-presentation of compiler construction has nowadays become rather seldom at South African universities, this short-paper is intended to serve as motivation and recipe for the topic's (re)introduction at other institutions of tertiary education.
On Computer Simulations, with particular Regard to their Application in Contemporary Astrophysics — some Science-Philosophical Considerations: DISCUSSION ABSTRACT
(2019-06-07) Bartelmann, Matthias; Gruner, Stefan
This 3-page abstract (with literature references) summarises the main points of our spoken presentation at the IACAP`2019 conference in Mexico City, June the 7th, 2019. A post-proceedings full-paper on this topic is in preparation.
Inappropriate Notions of 'Theory' and their Practical Consequences in the Discipline of Software 'Engineering': DISCUSSION ABSTRACT
(2019-06-06) Gruner, Stefan
This 3-page abstract (with literature references) summarises the main points of my spoken presentation at the IACAP`2019 conference in Mexico City, June the 6th, 2019. A post-proceedings full-paper on this topic is in preparation.
The Effects of Study Buddies and Study Hours in a First-Year Course on Operating Systems
(University of Cape Town, 2018) Stallmann, Christoph; Gruner, Stefan
Many university students, especially first-year students, struggle to efficiently manage their study time which results in lower academic achievements. This paper empirically examines the effect that the number of self-preparation hours of students has on their final grade. In addition, the influence of studying with a friend in preparation for tests and exams is analysed, in order to determine if it has any notable impact on students' academic performance. Five tests and exams of a first-year computer science module, namely operating systems, which is considered a difficult subject by students, were analysed for this study. Students were recommended to prepare for a certain number of hours, and before each test students were asked how much they actually studied and whether or not they prepared together with a friend. It was found that students who studied with a friend had a higher pass rate for all the tests compared to those who studied alone. Additionally, academic performance is by-and-large a matter of investing the recommended number of study hours, while in reality most students come to the exams underprepared. Students who passed the course had typically put in more preparation hours than their failing counterparts. Borderline students were also not able to substantially increase their marks with additional preparation.
Heinz Zemanek's almost forgotten contribution to the early Philosophy of Informatics
(University of Wollongong (Australia), 2016-12) Gruner, Stefan
This paper recapitulates some of the most important thoughts and aspects of the early and almost forgotten computer- and informatics-philosophy by the Austrian computer pioneer Heinz Zemanek (1920-2014). From a practical perspective, this remembrance has the two important purposes of preventing our contemporary discipline of computer-philosophy from the unneccessary 're-invention of the wheel' in many of its ongoing efforts, and of providing opportunities for Zemanek-inspired conflict resolutions in some cases where contemporary informatics-philosophical disputes appear to be stuck.
A Visual Modeling Technique for Controlling Graph Transformations
(Carleton Scientific, 2000) Gruner, Stefan; Kurt, Murat; Taentzer, Gabriele
Sophisticated control concepts are necessary to make the application of graph grammars feasible for practical graph grammar engineering and specification tasks. For this purpose we introduce hybrid control graphs based on the well known Activity Diagrams. Moreover, we present an interactive control graph tool showing the practical dimension of our concepts.
A Tool for Interactive Visualization of Distributed Algorithms
(2001) Gruner, Stefan; Mosbah, Mohamed; Bauderon, Michel
We present a tool for the visualization of distributed computations. Special attention is payed to certain distributed algorithms which have been coded as rewriting systems. In order to study the behaviour of algorithms and tool, several experiments have been performed the results of which are presented and discussed. Finally, some important properties of our tool are described and explained. A release of the tool is available to the public.
Parameterisation of three-valued abstractions
(2014) Timm, Nils; Gruner, Stefan; sg@cs.up.ac.za; CBSoft 2014 Brazilian Conference on Software : Theory and Practice (2014 : Maceio, Brazil) untranslated
Three-valued abstraction is an established technique in software model checking. It proceeds by generating an abstract state space model over the values true, false and unknown, where the latter value is used to represent the loss of information due to abstraction. Temporal logic properties can then be evaluated on such three-valued models. In case of an unknown result, the abstraction is iteratively refined, until a level of abstraction is reached where the property of interest can be either proven or refuted. In this paper, we introduce parameterised three-valued model checking. In our new type of abstract models, unknown parts can be either associated with the constant value unknown or with expressions over boolean parameters. Our parameterisation is an alternative way to state that the truth value of certain predicates or transitions is actually not known and that the checked property has to yield the same result under each possible parameter instantiation. A novel feature of our approach is that it allows for establishing logical connections between parameters: While unknown parts in pure three-valued models are never related to each other, our parameterisation approach enables to represent facts like 'a certain pair of transitions has unknown but complementary truth values', or 'the value of a predicate is unknown but remains constant along all states of a certain execution path'. We demonstrate that such facts can be automatically derived from the software system to be verified and that covering these facts in an abstract model can be crucial for the success and efficiency of checking temporal logic properties. Moreover, we introduce a fully automatic software verification framework based on counterexample-guided abstraction refinement and parameterisation.
Towards a Generic Design for General-Purpose Sensor Network Nodes
(SciTePress, 2010) Gruner, Stefan
The key to mature and efficient industrial software engineering is standardisation more than an aggressive struggle for innovation only for the sake of its own. This is assumption is also held for the area of sensor networks development, which is becoming an increasingly important field at the interface between software and hardware engineering. This short position paper proposes and outlines a generic design for the nodes of such sensor networks, which could be used in the future as the basis of almost any conceivable sensor network application. On such a basis of generic standardisation, the development of specific and particular sensor network applications will then be mainly a matter of hardware-independent programming with APIs, as it is already well known in the classical domain of operating systems in ordinary desktop PCs.
On the shortage of engineering in recent information systems research
(Australasian Association for Information Systems, 2014-12-08) Gruner, Stefan; Kroeze, Jan C.W.; sg@cs.up.ac.za; Australasian Conference on Information Systems, 25th : 2014 : Auckland, New Zealand
In this paper we argue that the so-called 'positivism'-versus-'interpretivism' conflict raised by some constructivist, postmodernist, relativist philosophers and methodologists in information systems research is merely a pseudo problem which has no basis in reality. This pseudo problem of so-called 'positivism' versus 'interpretivism' only distracts from the genuine problem of the information systems discipline, namely the design and construction of reliable devices from reasonable specifications, for well-defined purposes, on the basis of scientifically acceptable principles. In contrast to those relativist 'philosophies' we show that information systems research actually belongs to the domain of engineering which already has its time-tested methodology and epistemology, including a trinity of scientific-nomothetic, hermeneutic-idiographic, as well as pragmatic-normative elements. By accepting fact that information systems research is a specific instance of engineering research, which also includes (and has always included) the un-quantifiable 'human dimension', a number of fruitless debates can be terminated for the sake of genuine progress in information systems' theory, design and deployment.
Werkzeugspezifikation mit Schemakorrespondenzen
(Gesellschaft für Informatik (GI), 1997) Gruner, Stefan
Integration tools are important means for upholding the mutual consistency of dependent documents. In this work-in-progress-contribution (in German language) a new method for specifying such integration tools is sketched.
Why should Chemo-Engineers be interested in Graph Grammars? - A Solution to the Inconsistency Problem in Distributed Modeling
(Universität-Gesamthochschule Paderborn, Fachbereich Mathematik-Informatik, 1998-11) Gruner, Stefan
In distributed modeling, a group of developers are elaborating some specification in a work-sharing manner. Sub specifications and partial models are constructed according to a divide-and-conquer principle. Maintaining the consistency of the evolving sub specifications, generally called documents, is the main meta problem of distributed modeling. The volume of literature on consistency maintenance is vast, especially in the fields of classical software engineering. In this contribution it is shown how consistent document configurations can be coupled by graph schemas and graph grammars. Such models can serve as formal requirements definitions for various kinds of integration tools and consistency management systems. The approach presented here is not at all restricted to software engineering. As our team is busy in a long-term research project on software support for distributed modeling in chemical engineering, the running example in this contribution is taken from that engineering discipline.
Abstract Partial Deduction Challenged - (Extended Abstract)
(Springer-Verlag, 2003) Gruner, Stefan
Experiments have been conducted in order to determine to what extent Abstract Partial Deduction can infer implicit safety properties of the well-known Bakery Protocol.
A Combined Graph Schema and Graph Grammar Approach to Consistency in Distributed Modeling
(Springer-Verlag, 2000) Gruner, Stefan
In this overview-paper, a specification method based on coupled graph grammars is sketched that is able to uniformly describe consistent domain configurations which distributed modeling as well as re-engineering tasks are based on. The specification method supports the development of proper (re)-design tools, and the method is tool-supported itself.
Meta Typing is Compatible to the Typed SPO Approach
(Technische Universität Berlin, 2000) Gruner, Stefan
The main result of this contribution is that the presented concept of meta-typing is compatible to the SPO theory and can be implemented, therefore, into the SPO-based graph grammar engineering environment AGG without spoiling its formally sound basis.

Browse

Recent Submissions