List of Publications

S. Topalova, S. Zhelezova. The Cyclically Resolvable Steiner Triple Systems of Order 57. Mathematics 2025, 13, 212.

S. Topalova, S. Zhelezova. Parallelisms of PG(3,4) with a Great Number of Regular Spreads. Large-Scale Scientific Computing, I. Lirkov, S. Margenov eds., LNCS, 13952, Springer, 2024, ISBN:978-3-031-56208-2, ISSN:03029743, 16113349, SJR (Scopus):0.606

A. Betten, S. Topalova, S. Zhelezova. On parallelisms of PG(3,4) with automorphisms of order 2. Information and Computation, 301, art. 105201, Elsevier Inc., 2024, ISSN:0890-5401, SJR (Scopus):0.57, JCR-IF (Web of Science):0.8

S. Topalova, S. Zhelezova. Transitive Deficiency One Parallelisms of PG(3,7). Mathematics, 2023; 11 (11): 2458. SJR (Scopus):0.446, JCR-IF (Web of Science):2.4 Q1, (Web of Science)

A. Betten, S. Topalova, S. Zhelezova. Parallelisms of PG(3,4) invariant under an elementary abelian group of order 4. Applicable Algebra in Engineering, Communication and Computing 33, Springer, ISSN: 1432-0622, 2022, 649 – 674. SJR (Scopus):0.470, Q3 (Scopus)

S. Topalova, S. Zhelezova. Backtrack search for parallelisms of projective spaces. In: P. Flocchini, L. Moura (Eds.), Combinatorial Algorithms IWOCA 2021. LNCS 12757, Springer, ISBN: 978-3-030-79987-8, 2021, 544-557. SJR (Scopus):0.407, Q2 (Scopus)

S. Topalova, S. Zhelezova. Parallelisms of PG(3,5) with an automorphism group of order 25. In: Extended Abstracts EuroComb 2021, J. Nešetřil, G. Perarnau, J. Ruι, O. Serra (Eds.) Trends in Mathematics, 14, Springer Birkhδuser, ISBN: 978-3-030-83823-2, 2021, 668-674. SJR (Scopus):0.217, Q4 (Scopus)

S. Topalova, S. Zhelezova. New Parallelisms of PG(3,5) with Automorphisms of Order 8. In: F. Boulier, M. England, T.M. Sadykov, E.V. Vorozhtsov (Ed.) Computer Algebra in Scientific Computing, 23rd International Workshop, CASC 2021, Sochi, Russia, September 13–17, 2021, LNCS 12865, Springer, Cham, ISBN: 978-3-030-85164-4, 2021, 409-419. SJR (Scopus):0.407, Q2 (Scopus)

A. Betten, S. Topalova, S. Zhelezova. New Uniform Subregular Parallelisms of PG(3,4) Invariant Under an Automorphism of Order 2. Cybernetics and Information Technologies, 20, 6, Institute of Information and Communication Technologies - BAS, 2020, ISSN:1314-4081, DOI: 10.2478/cait-2020-0057, 18-27. SJR (Scopus):0.27, Q2 (Scopus)

S. Topalova, S. Zhelezova. Isomorphism and Invariants of Parallelisms of Projective Spaces. LNCS 12097, Springer, Cham, 2020, ISSN:03029743, 16113349, DOI:10.1007/978-3-030-52200-1_16, 162-172. SJR (Scopus):0.249, Q3 (Scopus)

A. Betten, S. Topalova, S. Zhelezova. Parallelisms of PG(3,4) invariant under cyclic groups of order 4. In: Ćirić M., Droste M., Pin JΙ. (eds) Algebraic Informatics. CAI 2019. Lecture Notes in Computer Science, 11545, Springer, Cham, 2019, ISBN:978-3-030-21362-6, DOI:https://doi.org/10.1007/978-3-030-21363-3_8, 88-99. SJR (Scopus): 0.427, Q2 (Scopus)

S. Topalova, S. Zhelezova. Types of spreads and duality of the parallelisms of PG(3,5) with automorphisms of order 13, October 2018, Designs Codes and Cryptography, DOI: 10.1007/s10623-018-0558-2. SJR (Scopus):0.549, JCR-IF (Web of Science):1.114,   Q1 (Scopus)

S. Zhelezova. A method for constructing splitting (v,u x c, lambda) BIBDs. Cybernetics and Information Technologies, Institute of Information and Communication Technologies – BAS 18 (5), 2018, 87 – 94. ISSN:1311-9702, SJR: 0.215, Q3 (Scopus)

S. Topalova, S. Zhelezova. New parallelisms of PG(3,4), Electronic Notes in Discrete Mathematics 57, Elsevier B.V., 2017, 193 – 198. ISSN:1571-0653, DOI:10.1016/j.endm.2017.02.032, SJR:0.262, Q3 (Scopus)

S. Topalova, S. Zhelezova. New regular parallelisms of PG(3,5). Journal of Combinatorial Designs, 24 (10), 2016, 473 – 482. ISSN:1520-6610, SJR:0.821, ISI IF:0.657, Q2 (Scopus)

S. Zhelezova. On regular parallelisms of PG(3,5) with automorphisms of order 5, Science. Business. Society, 1 (6), 2016, 3 – 5.

S. Topalova, S. Zhelezova. On point-transitive and transitive deficiency one parallelisms of PG(3,4), Designs, Codes and Cryptography, 75 (1), 2015, 9 – 19. DOI 10.1007/s10623-013-9887-3. ISSN 0925-1022, SJR: 0.564, IF 0.730

S. Topalova, S. Zhelezova. Doubly resolvable designs with small parameters, Ars Combinatoria 117, 2014, 289 – 302. ISSN: 0381-7032, SJR: 0.299, IF 0.204, Q3 (Scopus)

S. Topalova, S. Zhelezova. On transitive parallelisms of PG(3,4), Applicable Algebra in Engineering, Communication and Computing 24, (3-4), 2013, 159 – 164. ISSN 1432-0622, SJR: 0.462, IF 0.561, Q3 (Scopus)

S. Topalova, S. Zhelezova. Orthogonal resolutions and latin squares, Serdica Journal of Computing, 7 (1), 2013, 13-24. ISSN: 1312-6555.

S. Zhelezova, A method for classification of doubly resolvable designs and its application. Serdica Journal of Computing, 5 2011, 273–308. ISSN 1312-6555.

S. Topalova, S. Zhelezova. Transitive and orthogonal 2-parallelisms of PG(5,2) with automorphisms of order 31, Graphs and Combinatorics 26 (5), 2010, 727 - 735. ISSN 1435-5914, SJR:0.729, IF:0.242, Q2 (Scopus)

S.Zhelezova. Cyclic parallelisms of PG(5,2), Mathematica Balkanica 24 (1-2), 2010, 141 - 146. ISSN 0205-3217.

S. Topalova, S. Zhelezova. On an algorithm for a double resolvability test, Acta Universitatis Apulensis 15, 2008, 323-330. ISSN 1582-5329.

S.Zhelezova. Parallel class intersection matrices of orthogonal resolutions, Serdica Journal of Computing, 2, Num.4 (2008), 321-330. ISSN 1312-6555.

 

conference papers:

A. Tsvetanova, S. Zhelezova. Sorting in construction of resolutions of combinatorial designs. Mathematics and Education in Mathematics, 53, (Apr. 2024), 57 – 64.

S. Topalova, S. Zhelezova. Parallelisms of PG(n,q). Mathematics and Education in Mathematics, 51, (Apr. 2022), 113–123.

S. Topalova, S. Zhelezova. On parallelisms of PG(5,2) invariant under a cyclic subgroup of order 21. XVII International Symposium "Problems of Redundancy in Information and Control Systems" (REDUNDANCY), 25-29 October 2021, Moscow, Russian Federation, IEEE Xplore, ISSN: 2694-5215, 97-100, 2021.

S. Topalova, S. Zhelezova. Some parallelisms of PG(3,5) involving a definite type of spread, 2020 Algebraic and Combinatorial Coding Theory (ACCT), 2020, pp. 1-5, doi: 10.1109/ACCT51235.2020.9383404 (IEEExplore, Scopus)

S. Zhelezova. On the extension of a partial solution of d spreads to a parallelism, Mathematics and Education in Mathematics (2020) 173 – 177. ISSN:1313-3330.

A. Betten, S. Topalova and S. Zhelezova. Parallelisms of PG(3,4) invariant under a Baer involution. Proc. of the Sixteenth  International  Workshop  on  Algebraic and Combinatorial  Coding Theory, Svetlogorsk  (Kaliningrad region), Russia (2018), 57 – 61.

S. Zhelezova. A method for constructing splitting (v, u x c, l) BIBDs. Proc. of the Eighth International Workshop on Optimal Codes and Related Topics, July 10-14, Sofla, Bulgaria (2017), 134 – 141.

S. Topalova and S. Zhelezova. Parallelisms of PG(3,4) with automorphisms of order 3, Proc. of the Fifteenth International Workshop on Algebraic and Combinatorial Coding Theory, Albena, Bulgaria, (2016) 272 – 277.

S. Zhelezova, On regular parallelisms of PG(3,5) with automorphisms of order 5. Proc 4th International Conference on Technics. Technologies. Education. Safety, Information Technologies 2: Natural and Mathematical Sciences (2016) 72 – 74

S. Zhelezova, On regular partial parallelisms of PG(3,7) with automorphisms of order 5. Сборник Юбилейна конференция „25 години ВТУ“, 2016

A. Avdzhieva, T. Balabanov, G. Evtimov, D. Kirova, H. Kostadinov, T. Tsachev, S. Zhelezova, N. Zlateva. Optimal Cutting Problem. 113-th Еuropean Study Group with Industry, Problems and Final Reports, (2015), 49 – 61.

S. Zhelezova, On point-cyclic parallelisms of PG(3,7). Mathematics and Education in Mathematics (2015) 101 – 105. ISSN:1313-3330.

Ts. Baicheva, D. Bikov, Y. Borissov, L. Lazarova, A. Stojanova, L. Stoykova, S. Zhelezova, Finding an effective metric used for bijective S-Box generation by genetic algorithms. 104-th Еuropean Study Group with Industry, Problems and Final Reports (2014), 71-76. ISBN 978-954-9526-87-5

S. Topalova, S. Zhelezova, Parallelisms of PG(3,5) with automorphisms of order 13,  Proc. VII Intern.Workshop Optimal Codes and Related Topics (OC), Albena, Bulgaria (2013), 176-180.

N. Daskalova, P. Mateev, S. Zhelezova, Compressed representation of a partially defined integer function over multiple arguments. 95-th Еuropean Study Group with Industry, Problems and Final Reports (2013), 29-32. ISBN 978-954-9526-84-4.

S. Topalova, S. Zhelezova, Parallelisms of PG(3,4) with automorphisms of order 5, Proc. of the International Workshop on Algebraic and Combinatorial Coding Theory, Pomorie, Bulgaria (2012) 311 – 316. ISSN 1313-423X.

S.Zhelezova, The nonexistence of transitive 2-parallelisms of PG(5,3), Proc. of Annual Workshop on Coding Theory and Applications, Университетско издателство “Васил Априлов“ – Габрово (2011) 39-41. ISSN 1314-5134.

S. Topalova, S. Zhelezova, Parallelisms of PG(3,4) with automorphisms of order 7,  Proc. of the International Workshop Optimal Codes and Related Topics, Varna, Bulgaria  (2009) 184-188. ISSN 1313-1117.

S. Topalova, S. Zhelezova, Classification of doubly resolvable designs and orthogonal resolutions, Enhancing Cryptographic Primitives with Techniques from Error Correcting codes, in NATO Science for Peace and Security Series - D: Information and Communication Security, Vol. 23, B.Preneel, S.Dodunekov, V. Rijmen, S. Nikova eds., IOS Press, Amsterdam (2009), 260-264. ISBN 978-1-60750-002-5.

S. Topalova, S. Zhelezova, Classification of the 2-spreads of PG(5,2), Mathematics and Education in Mathematics (2008), 163-169. ISSN 1313-3330.

S. Topalova, S. Zhelezova, Sets of mutually orthogonal resolutions of BIBDs, Proc. XI Intern. Workshop on Algebraic and Combinatorial Coding Theory, Pamporovo, Bulgaria (2008), 280-285. ISSN 1313-423X.

S.Zhelezova, PCIMs in constructing doubly resolvable designs, Proc. V Intern. Workshop OC, White Lagoon, Bulgaria (2007) 260-266. ISBN:954-8986-18-3.

S. Topalova, S. Zhelezova, On the structure of doubly-resolvable 2-(21,3,1) designs, Proc. of X Intern. Workshop Algebraic and Combinatorial Coding Theory, Zvenigorod, Russia (2006) 263-268.

S. Topalova, S. Zhelezova, On the classification of doubly resolvable designs, Proc. IV Intern.Workshop Optimal Codes and Related Topics (OC), Pamporovo, Bulgaria (2005) 265-268, ISBN:954-8986-18-3.