Professor
Mathematical Sciences
Office
Marcus White Hall
111
Monday
8:50 am - 9:20 am
1:30 pm - 2:35 pm
Wednesday
8:50 am - 9:20 am
1:30 pm - 2:35 pm
Friday
8:50 am - 9:20 am
1:30 pm - 2:50 pm
Or by appointment
Education
Mathematics/Topology
Sofia University, Sofia, Bulgaria
1989
Mathematics/Topology
Sofia University, Sofia, Bulgaria
1984
Mathematics and Computer Science
Sofia University, Sofia, Bulgaria
1982
Areas of Expertise
  1. General, Categorical, and Geometric Topology and their Applications
    Product spaces; continuous extensions of functions defined on subspaces of product spaces; cardinal invariants; covering properties; compact, pseudocompact, countable compact and sequentially compact spaces; closure operators; P-minimal and P-closed spaces; sequential convergence; sequential spaces; extensions of topological spaces; supertopological spaces; neighborhood spaces; separation axioms; proximities; Noetherian spaces; applications of topology in number theory and geographic information systems.
  2. Graph Theory
    Hamiltonian graphs
Publications, Research & Presentations
  • Publications in peer-reviewed journals

    1.  Superneighborhood spaces and extensions of topological spaces,  80 (1986), no. 1, 31 鈥 43.
    2. Sequentially closed and absolutely closed spaces, Boll. Un. Mat. Ital. B(7) 1 (1987), no. 3, 849 鈥 860.
      Co-author: D. Dikranjan
    3. Topological spaces with no compactly determined extensions, , Sunny Beach, Bulgaria, April 6-9, (1988), 151 鈥 155.
    4. Sequentially P-closed spaces,  20 (1988), no. 1, 1 鈥 17.
       (The original publication is available via .)
    5. On sequential properties of Noetherian topological spaces,  28 (2004), No. 2, 487 鈥 501.
      Co-author: H. Minchev
       (The original publication is available via .)
    6. Dense C-embedded subspaces of products,  64 (2006), No. 3, 509 鈥 515.
      Co-authors: W. W. Comfort and L. Recoder-N煤帽ez
       (The original publication is available via .)
    7. M-embedded subspaces of certain product spaces,  155 (2008), No. 17-18, 2188 鈥 2195.
      Co-authors: W. W. Comfort and L. Recoder-N煤帽ez
       (The original publication is available via .)
    8. On the continuity of factorizations,  9 (2008), No. 2, 263 鈥 280.
      Co-authors: W. W. Comfort and L. Recoder-N煤帽ez
       (The original publication is available via .)
    9. Functional dependence on small sets of indices,  69 (2009), No. 3, 363 鈥 377.
      Co-author: W. W. Comfort
       (The original publication is available via .)
    10. Continuous mappings on subspaces of products with the 魏-box topology,  156 (2009), No. 16, 2600 鈥 2608.
      Co-author: W. W. Comfort
       (The original publication is available via .)
    11. On two conjectures about faulty hypercubes,  LVII (2009), 34 鈥 38.
      Co-authors: N. Casta帽eda, , F. Latour
    12. Path coverings with prescribed ends of the n-dimensional binary hypercube, Congr. Numer. 197 (2009), 193 鈥 205.
      Co-authors: N. Casta帽eda, , F. Latour
    13. Hamiltonian laceability of hypercubes with faults of charge one, Congr. Numer. 198 (2009), 15 鈥 30.
      Co-authors: N. Casta帽eda, , F. Latour
    14. On k-semi-perfect 1-factorizations of Qn and Craft's conjecture,  LVIII (2010), 36 鈥 41.
      Co-author: 
    15. On path coverings of hypercubes with one faulty vertex,  LVIII (2010), 42 鈥 47.
      Co-authors: N. Casta帽eda, , F. Latour
    16. Embedded paths and cycles in faulty hypercubes,  20 (2010), No. 3, 224 鈥 248.
      Co-author: N. Casta帽eda
       (The original publication is available at Springer via .)
    17. Classifying simple closed curve pairs on the 2-sphere and a generalization of the Schoenflies theorem, Topology Appl. 158 (2011), No. 6, 748 鈥 760.
      Co-authors: R. Franzosa and 
       (The original publication is available via .)
    18. Continuous extensions of functions defined on subsets of products,  159 (2012), No. 9, 2331 鈥 2337.
      Co-author: W. W. Comfort
       (The original publication is available via .)
    19. Continuous extensions of functions defined on subsets of products with the 魏-box topology,  42 (2013), 209 鈥 219.
      Co-authors: W. W. Comfort and D. Rivers
       (The original publication is available via .)
    20. The non-Hausdorff number of a topological space,  44 (2014), 249 鈥 256.
       (The original publication is available via .)
    21. Path coverings with prescribed ends in faulty hypercubes,  31 (2015), 833 鈥 869.
      Co-author: N. Casta帽eda
       (The original publication is available at Springer via .)
    22. Regular G未-diagonals and some upper bounds for cardinality of topological spaces,  149 (2016), No. 2, 324 鈥 337.
      Co-authors: M. Tkachenko and V. Tkachuk
      (The original publication is available at Springer via .)
    23. Cardinal invariants for 魏-box products: weight, density character and Souslin number,  516 (2016), 1 鈥 41.
      Co-author: W. W. Comfort
      (The original publication is available via .)
    24. The non-Urysohn number of a topological space,  43 (2017), No. 1, 223 鈥 235.
      (The original publication is available via .)
    25. Generalizations of two cardinal inequalities of Hajnal and Juh谩sz,  221 (2017), 425 鈥 431.
      (The original publication is available via .)
    26. Proof of Locke's conjecture, I,  6 (2017), No. 2, 345 鈥 371.
      Co-author: N. Casta帽eda
      (The original publication is available via .)
    27. Cardinal inequalities for Urysohn spaces involving variations of the almost Lindel枚f degree,  44 (2018), 195 鈥 212.
      (The original publication is available via .)
    28. More on the cardinality of S(n)-spaces,  44 (2018), 227 鈥 242.
      Co-author: L. Ko膷inac
      (The original publication is available via .)
    29. Cardinalities of weakly Lindel枚f spaces with regular G_魏-diagonals,  259 (2019), 80 鈥 89.
      (The original publication is available via .)
    30. Cardinal inequalities for S(n)-spaces,  159 (2019), No. 1, 229 鈥 245.
      (The original publication is available at Springer via .)
    31. Cardinal inequalities with Shanin number and 蟺-character, 29 (2022), no. 3, 389 鈥 403.
      Co-author: V. Tkachuk
      (The original publication is available at Project Euclid via .)
    32. More on cardinality bounds involving the weak Lindel枚f degree, 46 (2023), no. 4, 745 鈥 760.
      Co-authors:   and 
      (The original publication is available via .)
    33. On the upper bound of the cardinality of Hausdorff topological spaces, , 338 (2023), Article 108651.
      (The original publication is available via  .)
    34. On spaces with a 蟺-base with elements with compact closure,  118 (2024), no. 1, article 26.
      Co-authors:   and  
      (The original publication is available via  .)
       

     Submitted or Accepted for Publication

    1.  Strengthening of de Groot鈥檚 and Spadaro鈥檚 inequalities for Urysohn spaces (accepted for publication in , article 109643, available online 10/21/2025).
       

     Work in Progress

    1.  Proof of Locke's conjecture, II (preprint).
      Co-authors: N. Casta帽eda, , F. Latour
    2. On the infinitude of prime divisors of the range of a non-constant polynomial (preprint).
Memberships & Affiliations

American Mathematical Society (AMS)

Mathematical Association of America (MAA)

Courses Taught

Fall 2025

MWF 9:25 am - 10:35 pm - , EDB 111

MWF 10:50 am - 12:00 pm - , EDB 111

MWF 12:15 pm - 1:25 pm - , EDB 111

Calculus I

Calculus I

Calculus I

4 Calculus I

Calculus II

Calculus II

Calculus II

Calculus II

Office Hours Fall 2025 in MW 111

MWF 8:50 am 鈥 9:20 am, MW 1:30 pm 鈥 2:35 pm, F 1:30 pm 鈥 2:50 pm, 

or by appointment