13 research outputs found
Algebrai módszerek a Galois-geometriában = Algebraic methods in Galois-geometries
Páros q-ra stabilitási eredmĂ©nyt bizonyĂtottunk PG(2,q) páros halmazaira. Ez nĂ©gyzet q-ra Ă©les, Ă©s B. Segre Ăvek beágyazásárĂłl szĂłlĂł hĂres tĂ©telĂ©t általánosĂtja. Megmutattuk, hogy nĂ©gyzet q-ra PG(2,q)-ban 4qlog q Ă©s q^(3/2)-q+2q^(1/2) között minden mĂ©retű minimális lefogĂł ponthalmaz lĂ©tezik, sĹ‘t egy kicsit szűkebb intervallum minden Ă©rtĂ©kĂ©re q-ban több, mint polinomnyi. Magasabb dimenziĂłs projektĂv terekben a hipersĂkokat r modulo p pontban metszĹ‘ halmazok mĂ©retĂ©re bizonyos esetekben Ă©les alsĂł becslĂ©st adtunk, amely a maximális Ăvek nemlĂ©tezĂ©sĂ©re vonatkozĂł Ball-Blokhuis-Mazzocca tĂ©tel általánosĂtása. Ez oszthatĂł lineáris kĂłdok hosszára az n legalább (r-1)q+(p-1)r alsĂł becslĂ©st adja, ahol r az az Ă©rtĂ©k, amellyel n Ă©s minden kĂłdszĂł sĂşlya is oszthatĂł. Megmutattuk, hogy PG(2,q) reguláris szemioválisai csak az oválisok Ă©s az unitálok. Segre tĂpusĂş eredmĂ©nyt sikerĂĽlt belátni másod Ă©s magasabbrendű kĂşpok rĂ©szleges kĂşpszeletnyalábjaira. Kis minimális lefogĂł ponthalmazok struktĂşrájárĂłl azt sikerĂĽlt megmutatni, hogy ezek minden egyenest 1 modulo p^e pontban metszenek, ahol e osztja h-t, ha q=p^h. Ezen tĂşlmenĹ‘en, ha a metszet p^e+1 elemű, akkor az GF(p^e) feletti rĂ©szegyenes. Kis t-szeres lefogĂł ponthalmazokra az egyenesekkel valĂł metszetekre beláttuk, hogy azok modulo p t-vel kongruensek, ahol t a karakterisztika. Megmutattuk, hogy a Q(4,q) általánosĂtott nĂ©gyszögben nincsenek q^2-1 pontĂş maximális parciális ovoidok. PG(3m-1,q) sĂkokkal valĂł rĂ©szleges befedĂ©seire adtunk konstrukciĂłkat. | For even q-s we proved a stability theorem for sets of even type in PG(2,q). The result is sharp when q is a square, and it generalizes a famous embeddability theorem for arcs, due to B. Segre. It was proven that in PG(2,q), q square, there is a minimal blocking set for any size between 4qlog q and q^(3/2)-q+2q^(1/2), Moreover, for a slightly smaller interval we also proved that the number of nonisomorphic minimal blocking sets of that size is more than polynomial in q. For sets intersecting all hyperplanes in r modulo p points we found a lower bound that is sharp in some cases. The proof generalizes the nonexistence of maximal arcs, due to Ball-Blokhuis-Mazzocca. For divisible linear codes it gives that the length is at least (r-1)q+(p-1)r, where divides the length and the weight of all codewords. We found that in PG(2,q) regular semiovals must be either ovals or unitals. We obtained a Segre type theorem for partial flocks of the quadratic and general cones. About the structure of small minimal blocking sets we obtained the following: each line intersects the set in 1 modulo p^e points, where e divides h and q=p^h. Furthermore, if the intersection has p^e+1 points, then it is a subline over GF(p^e). We proved that a small minimal t-fold blocking set intersects every line in t modulo p points, where p is the characteristics. We also proved that the GQ Q(4,q) does not have maximal partial ovoids of size q^2-1. We gave constructions for partial plane spreads of PG(3m-1,q)
Kódelmélet és környéke = Coding theory and its neighbourhood
KĂłdelmĂ©letben hasznos vĂ©ges projektĂv terek speciális egyenes-, illetve hipersĂkmetszetű ponthalmazainak vizsgálata. Egyes cikkeinknek közvetlen kĂłdelmĂ©leti alkalmazása van (itt ezeket soroljuk), mások geometriai ill. algebrai szálakkal kapcsolĂłdnak oda. A polinomos mĂłdszer alkalmazásával bebizonyĂtottuk, hogy PG(2,q) egy olyan ponthalmaza, melyet minden egyenes adott r mod p pontban metsz, legalább (r-1)q+(p-1)r pontĂş kell legyen, ahol p a karakterisztika, r|q. KövetkezĂ©skĂ©pp egy 3 dimenziĂłs kĂłd,melynek hossza Ă©s sĂşlyai is oszthatĂłk r-rel Ă©s minimális távolsága legalább 3, legalább (r-1)q+(p-1)r hosszĂş kell legyen. Ball, Blokhuis Ă©s Mazzocca hĂres, maximális Ăvek nemlĂ©tezĂ©sĂ©rĹ‘l szĂłlĂł tĂ©tele is egyszerűen kijön a tĂ©telbĹ‘l. Meghatároztuk kĂ©t fontos poset, D^{k,n} Ă©s B_{m,n} automorfizmus-csoportját.A kĂ©rdĂ©skör az insertion-deletion kĂłdokhoz kapcsolĂłdik. A B_{m,n} struktĂşra automorfizmus-csoportja korábban is ismert volt, de a hosszĂş bizonyĂtást 1 oldalasra redukáltuk. Megfogalmaztunk egy sejtĂ©st algebrai sĂkgörbĂ©k pontjainak számárĂłl: n-edfokĂş, lineáris komponens nĂ©lkĂĽli görbĂ©nek legfeljebb (n-1)q+1 pontja lehet; (n-1)q+n/2-t sikerĂĽlt igazolni. Ilyen görbĂ©k hatĂ©kony kĂłdokat adnak. BebizonyĂtottuk, hogy ha egy lineáris [n,k,d]_q kĂłd kiterjeszthetĹ‘ nem feltĂ©tlenĂĽl lineáris [n+1,k,d+1]_q kĂłddá, akkor a kiterjesztĂ©st lineáris mĂłdon is meg lehet csinálni. EredmĂ©nyĂĽnk kiterjesztĂ©sĂ©bĹ‘l pedig az következhetne,hogy az MDS sejtĂ©s lineáris Ă©s tetszĹ‘leges kĂłdokra ekvivalens. | In coding theory, it is useful to study point sets of finite projective spaces with special intersection multiplicities with respect to lines and hyperplanes. Some of our papers have immediate application in coding theory (here we list those), the others are linked by its geometrical or algebraical concept. Using polynomial method, we proved that point sets of PG(n,q) intersecting each hyperplane in r mod p points have at least (r-1)q+(p-1)r points, where p is the characteristic and r|q. Hence a linear code whose length and weight are divisible by r and whose dual minimum distance is at least 3, has length at least (r-1)q+(p-1)r. Now the famous Ball-Blokhuis-Mazzocca theorem on the non-existence of maximal arcs becomes a corollary of this result. We determined the automorphism group of two important posets D^{k,n} and B_{m,n}. It was already known for B_{m,n}, but we shortened its long proof to 1 page. This topic is related to insertion-deletion codes. We conjecture that an algebraic plane curve of degree n without linear components can have at most (n-1)q+1 points, we showed that it is at most (n-1)q+n/2. Such curves give efficient codes. We proved that if a linear [n,k,d]_q code can be extended to a not necessarily linear[n+1,k,d+1]_q code then it can be done also in a linear way. From an extension of our results it would follow that the MDS-conjecture is equivalent for linear and arbirtary codes
VĂ©ges geometria = Finite geometry
Megmutattuk, hogy nĂ©gyzet q-ra PG(2,q)-ban 4qlog q Ă©s q^(3/2)-q+2q^(1/2) között minden mĂ©retű minimális lefogĂł ponthalmaz lĂ©tezik, sĹ‘t egy kicsit szűkebb intervallum minden Ă©rtĂ©kĂ©re q-ban több, mint polinomnyi. Magasabb dimenziĂłs projektĂv terekben a hipersĂkokat r modulo p pontban metszĹ‘ halmazok mĂ©retĂ©re bizonyos esetekben Ă©les alsĂł becslĂ©st adtunk, amely a maximális Ăvek nemlĂ©tezĂ©sĂ©re vonatkozĂł Ball-Blokhuis-Mazzocca tĂ©tel általánosĂtása. Ez oszthatĂł lineáris kĂłdok hosszára az n legalább (r-1)q+(p-1)r alsĂł becslĂ©st adja, ahol r az az Ă©rtĂ©k, amellyel n Ă©s minden kĂłdszĂł sĂşlya is oszthatĂł. Megmutattuk, hogy PG(2,q) reguláris szemioválisai csak az oválisok Ă©s az unitálok. Segre tĂpusĂ eredmĂ©nyt sikerĂĽlt belátni másodrendű kĂşpok rĂ©szleges kĂşpszeletnyalábjaira. Kis minimális lefogĂł ponthalmazok struktĂşrájárĂłl azt sikerĂĽlt megmutatni, hogy ezek minden egyenest 1 modulo p^e pontban metszenek, ahol e osztja h-t, ha q=p^h. Ezen tĂşlmenĹ‘en, ha a metszet p^e+1 elemű, akkor az GF(p^e) feletti rĂ©szegyenes. Kis t-szeres lefogĂł ponthalmazokra az egyenesekkel valĂł metszetekre beláttuk, hogy azok modulo p t-vel kongruensek, ahol t a karakterisztika. Ha q páros, akkor stabilitási eredmĂ©nyt bizonyĂtottunk PG(2,q) páros halmazaira. Az eredmĂ©ny nĂ©gyzet q-ra Ă©les, Ă©s B. Segre Ăvek beágyazásárĂłl szĂłlĂł hĂres tĂ©telĂ©t általánosĂtja. Megmutattuk, hogy a Q(4,q) általánosĂtott nĂ©gyszögben nincsenek q^2-1 pontĂş maximális parciális ovoidok. | It was proven that in PG(2,q), q square, there is a minimal blocking set for any size between 4qlog q and q^(3/2)-q+2q^(1/2), Moreover, for a slightly smaller interval we also proved that the number of nonisomorphic minimal blocking sets of that size is more than polynomial in q. For sets intersecting all hyperplanes in r modulo p points we found a lower bound that is sharp in some cases. The proof generalizes the nonexistence of maximal arcs, due to Ball-Blokhuis-Mazzocca. For divisible linear codes it gives that the length is at least (r-1)q+(p-1)r, where divides the length and the weight of all codewords. We found that in PG(2,q) regular semiovals must be either ovals or unitals. We obtained a Segre type theorem for partial flocks of the quadratic cone. About the structure of small minimal blocking sets we obtained the following: each line intersects the set in 1 modulo p^e points, where e divides h and q=p^h. Furthermore, if the intersection has p^e+1 points, then it is a subline over GF(p^e). We proved that a small minimal t-fold blocking set intersects every line in t modulo p points, where p is the characteristics. For even q-s we proved a stability theorem for sets of even type in PG(2,q). The result is sharp when q is a square, and it generalizes a famous embeddability theorem for arcs, due to B. Segre. We also proved that the GQ Q(4,q) does not have maximal partial ovoids of size q^2-1
DiszkrĂ©t Ă©s folytonos: a gráfelmĂ©let, algebra, analĂzis Ă©s geometria találkozási pontjai = Discrete and Continuous: interfaces between graph theory, algebra, analysis and geometry
Sok eredmĂ©ny szĂĽletett a gráfok növekvĹ‘ konvergens sorozataival Ă©s azok limesz-objektumaival, ill. az ezek vizsgálatára szolgálĂł gráf-algebrákkal kapcsolatban. Kidolgozásra kerĂĽltek a nagyon nagy sűrű gráfok (hálĂłzatok) matematikai elmĂ©letĂ©nek alapjai, Ă©s ezek alkalmazásai az extremális gráfelmĂ©let terĂĽletĂ©n. AktĂv Ă©s eredmĂ©nyes kutatás folyt a diszkrĂ©t matematika más, klasszikus matematikai terĂĽletekkel valĂł kapcsolatával kapcsolatban: topolĂłgia (a topolĂłgiai mĂłdszer alkalmazása gráfok magjára, ill a csomĂłk elmĂ©lete), geometriai szerkezetek merevsĂ©ge (a Molekuláris SejtĂ©s bizonyĂtása 2 dimenziĂłban), diszkrĂ©t geometriai (Bang sejtĂ©sĂ©nek bizonyĂtása), vĂ©ges geometriák (lefogási problĂ©mák, extremális problĂ©mák q-analogonjai), algebra (fĂ©lcsoport varietások, gráfhatványok szĂnezĂ©se), számelmĂ©let (additĂv számelmĂ©let, Heilbronn problĂ©ma), továbbá gráfalgoritmusok (stabilis párosĂtások, biolĂłgiai alkalmazások)) terĂĽletĂ©n. | Several results were obtained in connection with convergent growing sequences of graphs and their limit objects, and with graph algebras facilitating their study. Basic concepts for the study of very large dense graphs were worked out, along with their applications to extremal graph theory. Active and successful research was conducted concerning the interaction of discrete mathematics with other, classical areas of mathematics: topology (applications of topology in the study of kernels of graphs, and the theory of knots), rigidity of geometric structures (proof of the Molecular Conjecture in 2 dimensions), discrete geometry (proof of the conjecture of Bang), finite geometries (blocking problems, q-analogues of extremal problems), algebra (semigroup varieties, coloring of graph powers), number theory (additive number theory, heilbronn problem), and graph algorithms (stable matchings, applications in biology)
Synthesis, biochemical, pharmacological characterization and in silico profile modelling of highly potent opioid orvinol and thevinol derivatives
Predicting Clinical Progression in Multiple Sclerosis With the Magnetic Resonance Disease Severity Scale
Quantification of ricin, RCA and comparison of enzymatic activity in 18 Ricinus communis cultivars by isotope dilution mass spectrometry
Educate or serve: the paradox of “professional service” and the image of the west in legitimacy battles of post-socialist advertising
This article investigates a puzzle in the rapidly evolving profession of advertising in post-socialist Hungary: young professionals who came of age during the shift to market-driven practices want to produce advertising that is uncompromised by clients and consumers, and to educate others about western modernity. It is their older colleagues—trained during customer-hostile socialism—who emphasize that good professionals serve their clients’ needs. These unexpected generational positions show that 1) professions are more than groups expanding their jurisdiction. They are fields structured by two conflicting demands: autonomy of expertise and dependence on clients. We can explain the puzzle by noting that actors are positioning themselves on one or the other side based on their trajectory or movement in the field relative to other actors. Old and new groups vie for power in the transforming post-socialist professional field, responding to each other’s claims and vulnerabilities, exploiting the professional field’s contradictory demands on its actors. 2) The struggle is not between those who are oriented to the west and those that are not. Rather, the west is both the means and the stake of the struggle over historical continuity and professional power. Imposing a definition of the west is almost the same as imposing a definition of the profession on the field. In this historical case, “field” appears less as a stable structure based on actors’ equipment with capital, than as dynamic relations moved forward by contestation of the field’s relevant capital