Program kolokvií s abstrakty pro semestr Podzim 1998

29. 9. 1998

Výzkumné záměry FI

Abstract:

• prof. RNDr. J. Gruska, DrSc: Kvantova informace a pocitani
• doc. Ing. J. Staudek, CSc.: Bezpecnostni politiky v informacnich technologiich
• doc. Ing. J. Sochor, CSc.: Interakce cloveka s pocitacem
• doc. RNDr. M. Kretinsky, CSc.: Paralelni a distribuovane systemy
• doc. PhDr. K. Pala, CSc.: Informacni technologie ve zpracovani prirozeneho jazyka
• doc. RNDr. I. Kopecek, CSc.: Dialogove systemy a dialogove programovani s aplikacemi v oblasti asistivnich technologii
• Mgr. M. Kozubek, Dr.: Aplikace pocitacove analyzy obrazu v cytogenetice

6. 10. 1998

Bing Wu, Trinity College, Dublin, Ireland

Legacy Information Systems: The Problems and Possible Solutions

Abstract: Legacy information systems typically form the backbone of the information flow within an organisation and are the main vehicle for consolidating information about the business. As a solution to the problems these systems pose - brittleness, inflexibility, isolation, non-extensibility, lack of openness etc. - many companies are migrating their legacy systems to a new environment which allow the information system to easily adapt to new business requirements.
This talk is to provide an overview on the Migrations of Legacy Information Systems. First, it discusses the legacy system problem, and briefs the possible solutions. Second, the main emphasis is given for the detailed discussion on the evolutionary approach for the legacy system problem: legacy systems migration. Two main current available approaches of migration : Gateway-based Chicken Little approach, and Gateway-free Butterfly Methodology are presented in detail. A brief comparison between these two method is also given. Finally, some possible future research topics and directions are outlined.

13. 10. 1998

Ivan Kopecek, FI MU Brno

DIALOG - programovani se zavrenyma ocima

Abstract: Programovaci system DIALOG je nove paradigma, ktere bylo inspirovano snahou o vyvoj podpory programovani pro zrakove postizene. Paradoxne ze ukazalo, ze mnohe principy jsou obecne a vedou ke zcela novemu pohledu. Hlavni rysy DIALOGu jsou:
- programovani zalozene na dialogu s podporou prirozene reci
- vysoka konsistence a v dusledku toho i jednoduchost jazyka
- plna integrovanost systemu
- objektova orientace (v ponekud netradicnim smyslu)
- strukturovana orientovanost
DIALOG je prvnim jazykem, ktery neni jazykem v klasickem smyslu (neni to podmnozina volneho monoidu) a ktery tedy opousti predstavu jazyka psaneho na papire. DIALOG je system vyvijeny na FI, evokujici mnoho zajimavych praktickych i teoretickych problemu.

P.S.: V DIALOGu se bude jednou programovat. Bud pro to, ze:
A) je to tak dobry system nebo
B) si programovanim v klasickych jazycich znicite oci.


A) je spravne :-)

20. 10. 1998

J. Cernocky, FEI VUT Brno

Speech Processing using Automatically Derived Segmental Units: Applications to Very Low Rate Coding and Speaker verification

Abstract: Sub-word units are widely used in various domains of speech processing. Classically, they are based on phonemes or their derivatives (context-dependent phonemes, syllables, etc.) and to be determined, an important amount of phonetic and linguist knowledge is necessary. In order to train a speech processing system, one must dispose of annotated training database (DB). The annotation using phonetically-derived units is a time-consuming, costly and error-prone task.
Even if natural language processing can not be done without phonetic and/or linguist expertise, recent advances in Automatic Language Independent Speech Processing (ALISP) have shown, that many tasks relying currently on such knowledge can be performed more efficiently using data-driven approaches.
Among various ALISP tools, we use the Temporal Decomposition (introduced by Atal in 82, refined by Bimbot) for the determination of segment borders, and the unsupervised clustering, represented by the Vector Quantization (VQ) for assignment to classes. The segmental units are modeled by Hidden Markov Models (HMM) - those are initialized using the original TD+VQ transcriptions and refined in successive steps of corpus segmentation and parameter set re-estimation. Experiments were performed also with Multigrams (MG), as pre- or post-processing for HMMs.
The use of this method is demonstrated on a very low bit-rate speech vocoder. In the coder, the incoming speech is segmented into coding units and their indices are transmitted. The decoder includes a speech synthesizer, which concatenates examples of coding units (``representatives'') drawn from the training corpus. In speaker-dependent experiences, performed with PolyVar and Boston University databases, intelligible speech was obtained at mean bit rate of 120 bps for transmission of unit indices. A side-information is nevertheless needed for the transmission of representative choice and for the prosody.
Another application of these units is in text-independent speaker verification. It is known, that discriminative powers of different phonemes are not equal and that phoneme-based verification systems perform better than ``global'' ones. In case a speech recognizer is not available, ALISP units may serve to segment and classify the speech for a verification system. This approach was tested with a Multi-Layer Perceptron (MLP) during NIST-NSA 98 evaluation campaign. The results have shown the superiority of this approach over the global MLP system.

27. 10. 1998

Petr Hanacek, FEI VUT Brno

Bezpecnost elektronickych penez

Abstract: Tematem prednasky bude problematika bezpecnosti elektronickych plateb a predevsimm jedne jejich podoby - elektronickych penez.
V poslednich letech se objevuje stale vetsi tlak na vyvoj systemu elektronickeho obchodu. Funkcni system elektronickeho obchodu je vsak velmi obtizne vytvorit bez odpovidajiciho systemu pro elektronicke provedeni platby. Je samozrejme mozne pouzit nektery z konvencnich platebnich systemu (napriklad platebni karty, seky nebo platebni prikazy), avsak tyto instrumenty neodpovidaji soucasnym pozadavkum na kvalitu a rychlost elektronickeho obchodu. Vysledny system elektronickeho obchodu by totiz mel vsechny nedostatky, zdedene z techto platebnich instrumentu. Proto se vyvijeji nove elektronicke platebni systemy, jejichz hlavnim cilem dnes je prevest konvencni penize na jejich elektronicky ekvivalent - elektronicke penize.
Vzhledem k tomu, ze v oblasti elektronickych platebnich systemu je v soucasnosti ponekud neprehledna situace, príspevek se bude snazit zavest take taxonomii pro klasifikaci techto systemu podle ruznych hledisek.
Problematika elektronickych penez je tesne svazana s problematikou bezpecnosti informacnich systemu a predevsim kryptografie. Navrh pouze funkcniho elektronickeho platebniho systemu je jednoduchy. Navrh funkcniho a bezpecneho (tj. odolneho proti podvodu) platebniho systemu je vsak pomerne slozity a bezpecnostni mechanismy casto tvori nejdulezitejsi cast systemu. Tato problematika bude ilustrována na konkretnim prikladu elektronicke penezenky.

3. 11. 1998

Antonin Kucera, TU Munchen and FI MU

Bisimulation and Simulation Games: Infinite vs. Finite-State Systems

Abstract: The `semantical sameness' of two concurrent processes X,Y is often defined by means of bisimulation- and simulation-like games on the transition systems which are associated with X and Y. Those games are played by two players, Al and Ex; Al repeatedly `attacks' Ex by his moves, and Ex has to `defend' each of those individual moves by performing his own move which is consistent with the rules. Al wins the game if after a finite number of rounds Ex cannot defend the Al's final attack. Processes X and Y are then considered to be the `same' iff Ex has a universal defending strategy. (i.e., Al cannot win the game if Ex plays sufficiently clever).
As the processes X,Y can have infinitely many states, an existence of defending strategy for Ex is generally undecidable. We concentrate just on the sub-case when X is infinite-state, while Y is guaranteed to have only finitely-many states. We design a general method which says how to establish decidability of the problem whether Ex has a defending strategy in a bisimulation-like game. We also show that this method can be successfully applied to various classes of infinite-state processes (where X can be chosen from) and various bisimulation-like equivalences (in particular the strong and the weak bisimulation equivalence). We also show that there is a close relationship with the model-checking problem for a simple temporal logic EF.
Then we examine the analogous problem(s) for simulation games. As we shall see, decidability issues for bisimulation- and simulation-like games are rather different, although there is an interesting and general relationship between bisimulation and simulation which will be also precisely formulated (and applied). Finally, we present some decidability/undecidability results for concrete process classes.
The first part of the talk is based on a joint work with P. Jancar and R. Mayr which has been presented at Icalp'98. The second part contains some recent (unpublished) results.

10. 11. 1998

Dana Pardubska, KVI MFF UK, Bratislava

OBDD's - Ordered Binary Decision Diagrams

Abstract: Vdaka svojim algoritmickym vlastnostiam sa OBDD stali oblubenou datovou strukturou v oblasti CAD, testovania a verifikacie digitalnych systemov. Su velmi efektivnym nastrojom za podmienky, ze ich velkost neprekroci istu kriticku hranicu. Vo vseobecnosti su OBDD velmi citlive na poradie testovania premennych - su zname az exponencialne rozdiely vo velkosti ekvivalentnych OBDD v zavislosti od poradia premennych. Preto je prirodzene, ze problemu optimalizacie velkosti OBDD sa venuje velka pozornost. Kedze je tento problem NP-tazky, v praxi sa na jeho riesenie pouzivaju rozne heuristiky.
Prednaska predstavi OBDD, ich vlastnosti a problematiku optimalizacie ich velkosti. Prezentujeme najucinnejsie zname heuristiky spolu s algoritmami na manipulaciu s OBDD.

17. 11. 1998

Jiri Zara, FEL CVUT Praha

Konstrukce BSP stromu pro urychlovani metody sledovani paprsku

Abstract: Rozdeleni trojrozmerneho prostoru a jeho reprezentace pomoci hierarchickych datovych struktur je jednim ze zakladnich prostredku ke snizeni vypocetniho casu pro radu uloh zalozenych na vyhledavani objektu dle zadanych podminek. K nejpropracovanejsim datovym strukturam patri binarni stromy - BSP (Binary Space Partitioning trees). Jejich specialni pripad zalozeny na ortogonalnim deleni prostoru nachazi efektivni uplatneni v pocitacove grafice, zejmena v ulohach vrhani paprsku (ray casting, ray tracing).
Pro konstrukci BSP stromu se pouzivaji ruzna kriteria - vyvazenost stromu, minimalizace poctu objektu v listech, heuristicky pristup. Stejne tak lze BSP strom reprezentovat ruznymi datovymi strukturami, jejichz tvar ovlivnuje efektivitu nasledneho traverzovani.
V prednasce budou diskutovana ruzna kriteria tvorby ortogonalnich BSP stromu a jim odpovidajici datove struktury. Dale budou uvedeny algoritmy traverzovani BSP stromu s ohledem na metodu sledovani paprsku.

24. 11. 1998

Ivana Kolingerova, ZCU Plzen

Konstrukce trojuhelnikovych a ctyrstenovych siti

Abstract: Trojuhelnikové a ctyrstenove site hraji vyznamnou ulohu v aproximacich, metode konecnych prvku, numericke analyze, CAGD, pocitacove grafice, pocitacovem videni, robotice atd. Proto postupne vzniklo mnoho metod konstrukce trojuhelnikovych siti - triangularizaci a ctyrstenovych siti - tetrahedronizaci. Metody se lisi pozadavky na vysledne site, výpočetní sloľitostí, náročností implementace, numerickou stabilitou.
Prednaska strucne rekapituluje zakladni triangularizace a tetrahedronizace a jejich vlastnosti. Duraz bude kladen take na spolecne a rozdilne rysy siti v E2 a v E3. Krome prehledu existujicich metod budou zahrnuty take puvodni vysledky.

1. 12. 1998

Peter Ruzicka, MFF UK Bratislava

Interval Routing Schemes : A Survey

Abstract: We survey the classical and also the most recent results achieved in the field of Interval Routing Schemes, a well-known strategy to realize distributed routing algorithms in a compact way. These results are classified in several themes: characterization, compactness and shorthest path, dilation and stretch factors, congestion, specific class of graphs (interconnection networks, planar, bounded degree, chordal rings,...), and other recent extentions including deadlock-free, multi-dimensional, and distributed problems related to Interval Routing Schemes. For some of these themes we present a state of the art and several open questions.

8. 12. 1998

Herbert Wiklicky, Universitat Mannheim, Germany

Linear Operators in Semantics

Abstract: This talk introduces a new approach towards the semantics of Concurrent Constraint Programming (CCP), which is based on operator algebras. In particular, we show how (stochastic) matrices can be used for modelling both a quantitative version of nondeterminism (in the form of a probabilistic choice) and synchronisation. We will assume Probabilistic Concurrent Constraint Programming (PCCP) as the reference paradigm. The presented model subsumes CCP as a special case.
The model is obtained by a fixpoint construction on a space of linear operators. For the purpose of this talk, we consider only finite constraint systems. This allows us to define our model by using finite dimensional linear operators, i.e. matrices. We show that this model is equivalent to a notion of observables which extends the standard one in CCP (input/output behaviour) by including information about the likelihood of the computed results. The model also captures infinite computations.

15. 12. 1998

Radim Jirousek, VSE Praha

Reprezentace mnoharozmernych distribuci bayesovskymi sitemi

Abstract: V leckterých pravděpodobnostních modelech umělé inteligence je třeba pracovat s distribucemi vysokých dimenzí (řádově stovky ci tisíce). Pro tyto účely vznikly grafické markovské modely, které pro efektivní reprezentaci takových distribucí vhodně vyuľívají vlastnosti podmíněné nezávislosti. V přednáące budou zavedeny dva nejdůleľitějąí z těchto modelů, bayesovské sítě a rozloľitelné modely. Dále bude naznačeno, jakými způsoby lze v těchto modelech provádět výpočty.