New Type of Coding Problem Motivated by Database Theory

The present paper is intended to survey the interaction between relational database theory and coding theory. In particular it is shown how an extremal problem for relational databases gives rise to a new type of coding problem. The former concerns minimal representation of branching dependencies that can be considered as a data mining type question. The extremal configurations involve d-distance sets in the space of disjoint pairs of k-element subsets of an n-element set X. Let X be an n-element finite set, 0 < k < n/2 an integer. Suppose that {A(1), B-1} and {A(2), B-2} are pairs of disjoint k-element subsets of X (that is, \A(1)\ = \B-1\ = \A(2)\ = \B-2\ = k, A(1) boolean AND B-1 = 0, A(2) boolean AND B-2 = 0). Define the distance of these pairs by d({A(1), B-1}, {A(2), B-2}) = min{\A(1) - A(2)\ + \B-1 - B-2\, \A(1) - B-2\ + \B-1 - A(2)\). (C) 2004 Elsevier B.V. All rights reserved

Kerámia gömbhéjjal töltött szintaktikus fémhabok törésmechanikai vizsgálata

A fémmátrixú szintaktikus fémhabok számos terülten alkalmazhatóak: légi járművek vagy autóipari ütköző zónák energiaelnyelő elemeiként, védőburkolatokként. Jelen kutatómunka kerámia gömbhéjakkal töltött Al99,5 és AlSi12 mátrixú szintaktikus fémhabok törésmechanikai méréstechnikájával foglalkozik. Munkánk során bemetszett próbatesteket vetettünk alá 3-pontos hajlító vizsgálatnak, amelyből repedéskinyílás-nyomóerő görbéket kaptunk. Az eredményeket kiértékelve KQ (bizonyos feltételekkel KIC) meghatározható az adott anyagokra

Magna Moravia, Szvatopluk országa : hol voltak a morva végek?

According to the contemporary sources, before the conquest of the Carpathian Basin during the 9th century, a Slavic principality was formed on the central Balkan and the southern territories of the Carpathian Basin, which can be matched with Magna Moravia (Old Moravia) mentioned by the DAI, thus, Svatopluk's country. However, this early organisation was not the national state of the Western-Slavic Moravians, but - according to Boba Imre - a patrimonial part of a greater condominium, which had a similar construction of that of the Rus, and was established on South-Slavic territory, as opposed to „northern Moravia", the prototype of the later Moravian marquisate. On this territory the episcopate was reestablished with the lead of Method in Syrmium, „Moravia of Pannónia" in the year 869, after the Avar's conquest of the territory in 582. Scholars tried to verify the location of Old Moravia north of the Danube by reinterpretation of the sources on one hand, and by revaluation of the late Avar archeological material of the Moravian Basin as Slavic on the other. Likewise, the experiments to locate Magna Moravia on the Hungarian Great Plain failed, since there is no relevant material belonging to the 9th century there. Thus, for the location of Svatopluk's country the southern zone of the Great Plain could be considered, as well as Syrmia, the central parts of the Balkan, and the blank of the river Sava. However, neither the archeological researches on the Balkan nor thenhistorical interpretations provide sufficent infromation, these are future tasks of archeology