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Papers by Alex Rosa
North-Holland Mathematics Studies, 1982
North-Holland Publishing Company, 1982 All rights reserved. No part of this publication may be re... more North-Holland Publishing Company, 1982 All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior ...
Journal of Graph Theory, 1997
The triangle-spectrum for 2-factorizations of the complete graph Kv is the set of all numbers δ s... more The triangle-spectrum for 2-factorizations of the complete graph Kv is the set of all numbers δ such that there exists a 2-factorization of Kv in which the total number of triangles equals δ. By applying mainly design-theoretic methods, we determine the triangle spectrum for all v ≡ 1 or 3 (mod 6), v ≥ 43, as well as for v = 7, 9, 13, 15, 21, and 27. For orders v = 19, 25, 31, 33, 37, 39, we leave only a total of 11 values undecided. To determine the triangle-spectrum for v ≡ 5 (mod 6) remains an open problem. © 1997 John Wiley & Sons, Inc. J Graph Theory 26: 83–94, 1997
Journal of Graph Theory, 1995
... notion of bandsize of a graph, may be called the gracesize of G, gs(G). Because of the famous... more ... notion of bandsize of a graph, may be called the gracesize of G, gs(G). Because of the famousgraceful tree conjecture, it could be interesting to prove nontrivial lower bounds on the gracesize of trees. In this paper, we restrict ourselves to bipartite labelings of trees, and consider ...
European Journal of Combinatorics, 1985
It is shown that the complete graph K" has a cyclic !-factorization if and only if n is even and ... more It is shown that the complete graph K" has a cyclic !-factorization if and only if n is even and n,.; 2', t;;. 3.
Le Matematiche, 1993
... Configurations in triple systems: avoidance and decomposition. AlexRosa. Abstract. See direct... more ... Configurations in triple systems: avoidance and decomposition. AlexRosa. Abstract. See directly the article. Full Text: pdf.
About DML-CZ | FAQ | News | Conditions of Use | Math Archives | Contact Us. Previous | Up | Next.... more About DML-CZ | FAQ | News | Conditions of Use | Math Archives | Contact Us. Previous | Up | Next. DML-CZ Home; Mathematica Slovaca; Volume 44; Issue 3. Article. First Page Preview. Plesník, Ján ; Porubský, Štefan ; Rosa, Alexander ...
European Journal of Combinatorics, 1989
Journal of Combinatorial Designs, 2000
We settle completely the existence of symmetric graph designs on friendship graphs.
The Electronic Journal of Combinatorics, 2010
We survey the basic properties and results on Steiner systems S(2, 4, v), as well as open problems.
A Steiner triple system (briefly STS) is a pair where S is a finite set and is a collection of 3-... more A Steiner triple system (briefly STS) is a pair where S is a finite set and is a collection of 3-subsets of S (called triples) such that every pair of distinct elements of S belongs to exactly one triple of . The number |S| is called the order of . It is well-known that there is an STS of order if and only if or 3 (mod 6). Therefore in saying that a certain property concerning STS is true for all it is understood that or 3 (mod 6). An STS of order v will sometimes be denoted by .
Mathematica Slovaca, 1992
Institute of Mathematics of the Academy of Sciences of the Czech Republic provides access to digi... more Institute of Mathematics of the Academy of Sciences of the Czech Republic provides access to digitized documents strictly for personal use. Each copy of any part of this document must contain these Terms of use.
Journal of Graph Theory, 1997
North-Holland Publishing Company, 1982 All rights reserved. No part of this publication may be re... more North-Holland Publishing Company, 1982 All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior ...
North-Holland Mathematics Studies, 1982
North-Holland Publishing Company, 1982 All rights reserved. No part of this publication may be re... more North-Holland Publishing Company, 1982 All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior ...
Journal of Graph Theory, 1997
The triangle-spectrum for 2-factorizations of the complete graph Kv is the set of all numbers δ s... more The triangle-spectrum for 2-factorizations of the complete graph Kv is the set of all numbers δ such that there exists a 2-factorization of Kv in which the total number of triangles equals δ. By applying mainly design-theoretic methods, we determine the triangle spectrum for all v ≡ 1 or 3 (mod 6), v ≥ 43, as well as for v = 7, 9, 13, 15, 21, and 27. For orders v = 19, 25, 31, 33, 37, 39, we leave only a total of 11 values undecided. To determine the triangle-spectrum for v ≡ 5 (mod 6) remains an open problem. © 1997 John Wiley & Sons, Inc. J Graph Theory 26: 83–94, 1997
Journal of Graph Theory, 1995
... notion of bandsize of a graph, may be called the gracesize of G, gs(G). Because of the famous... more ... notion of bandsize of a graph, may be called the gracesize of G, gs(G). Because of the famousgraceful tree conjecture, it could be interesting to prove nontrivial lower bounds on the gracesize of trees. In this paper, we restrict ourselves to bipartite labelings of trees, and consider ...
European Journal of Combinatorics, 1985
It is shown that the complete graph K" has a cyclic !-factorization if and only if n is even and ... more It is shown that the complete graph K" has a cyclic !-factorization if and only if n is even and n,.; 2', t;;. 3.
Le Matematiche, 1993
... Configurations in triple systems: avoidance and decomposition. AlexRosa. Abstract. See direct... more ... Configurations in triple systems: avoidance and decomposition. AlexRosa. Abstract. See directly the article. Full Text: pdf.
About DML-CZ | FAQ | News | Conditions of Use | Math Archives | Contact Us. Previous | Up | Next.... more About DML-CZ | FAQ | News | Conditions of Use | Math Archives | Contact Us. Previous | Up | Next. DML-CZ Home; Mathematica Slovaca; Volume 44; Issue 3. Article. First Page Preview. Plesník, Ján ; Porubský, Štefan ; Rosa, Alexander ...
European Journal of Combinatorics, 1989
Journal of Combinatorial Designs, 2000
We settle completely the existence of symmetric graph designs on friendship graphs.
The Electronic Journal of Combinatorics, 2010
We survey the basic properties and results on Steiner systems S(2, 4, v), as well as open problems.
A Steiner triple system (briefly STS) is a pair where S is a finite set and is a collection of 3-... more A Steiner triple system (briefly STS) is a pair where S is a finite set and is a collection of 3-subsets of S (called triples) such that every pair of distinct elements of S belongs to exactly one triple of . The number |S| is called the order of . It is well-known that there is an STS of order if and only if or 3 (mod 6). Therefore in saying that a certain property concerning STS is true for all it is understood that or 3 (mod 6). An STS of order v will sometimes be denoted by .
Mathematica Slovaca, 1992
Institute of Mathematics of the Academy of Sciences of the Czech Republic provides access to digi... more Institute of Mathematics of the Academy of Sciences of the Czech Republic provides access to digitized documents strictly for personal use. Each copy of any part of this document must contain these Terms of use.
Journal of Graph Theory, 1997
North-Holland Publishing Company, 1982 All rights reserved. No part of this publication may be re... more North-Holland Publishing Company, 1982 All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior ...