IPM Positions

Resident Researcher, School of Mathematics (2014 - 2017 (From December 22))

Past IPM Positions

Resident Researcher, School of Mathematics (2009 - 2012) Associate Researcher, School of Mathematics (2002 - 2003) Post-Doctoral Research Fellow, School of Mathematics (1999 - 2001)

Non IPM Affiliations

Professor of Shahid Beheshti University

Research Interests

Combinatorics: Graph Coloring, Probabilistic Methods, Algebraic Combinatorics and their Interconnections.

Present Research Project at IPM

Graphs Homomorphism and Circular chromatic number of graphs

Related Papers

1.	H. Hajiabolhassan (Joint with M. Alishahi) Chromatic number of random kneser hypergraphs J. Combin. Theory Ser. A (Accepted) [abstract]

2.	H. Hajiabolhassan (Joint with M. Alishahi and F. Meunier) Strengthening topological colorful results for graphs European J. Combin. 64 (2017), 27-44  [abstract]

3.	H. Hajiabolhassan (Joint with F. Moazami) Secure frameproof codes through biclique covers DIMACS Ser. Discrete Math. Theoret. Comput. Sci. 14 (2012), 261-270  [abstract]

4.	H. Hajiabolhassan (Joint with F. Moazami) Some new bounds for cover-free families through biclique covers Discrete Math. (Accepted) [abstract]

5.	H. Hajiabolhassan A generalization of Kneser's conjecture Discrete Math. 311 (2011), 2663-2668  [abstract]

6.	A. Daneshgar and H. Hajiabolhassan Unique list-colourability and the fixing chromatic number of graphs Discrete Appl. Math. 152 (2005), 123-138  [abstract]

7.	A. Daneshgar and H. Hajiabolhassan Random walks and graph homomorphisms DIMACS Ser. Discrete Math. Theoret. Comput. Sci. 63 (2004), 49-63  [abstract]

8.	H. Hajiabolhassan and X. Zhu Sparse H-colourable graphs of bounded maximum degree Graphs Combin. 20 (2004), 65-71  [abstract]

9.	Y. G. Ganjali, M. Ghebleh, H. Hajiabolhassan, M. Mirzazadeh and B. S. Sadjad Uniquely 2-list colorable graphs Discrete Appl. Math. 119 (2003), 217-225  [abstract]

10.	H. Hajiabolhassan and X. Zhu Circular chromatic number and Mycielski construction J. Graph Theory 44 (2003), 106-115  [abstract]

11.	A. Daneshgar and H. Hajiabolhassan Graph homomorphisms through random walks J. Graph Theory 44 (2003), 15-38  [abstract]

12.	H. Hajiabolhassan and X. Zhu Circular chromatic number of subgraphs J. Graph Theory 44 (2003), 95-105  [abstract]

13.	H. Hajiabolhassan, M. Ghebleh and Ch. Eslahchi Some concepts in list coloring J. Combin. Math. Combin. Comput. 41 (2002), 151-160  [abstract]

14.	R. Tusserkani, H. Hajiabolhassan and M. L. Mehrabadi Minimal coloring and strength of graphs Discrete Math. 215 (2000), 265-270  [abstract]

15.	H. Hajiabolhassan, M. L. Mehrabadi and R. Tusserkani A note on the Hall-condition number of a graph Ars Combin. 55 (2000), 215-216  [abstract]

16.	H. Hajiabolhassan, M.L. Mehrabadi, R. Tusserkani and M. Zaker A characterization of uniquely vertex colorable graphs using minimal defining sets Discrete Math. 199 (1999), 233-236  [abstract]

17.	M.L. Mehrabadi and H. Hajiabolhassan On clique polynomials Australas. J. Combin. 18 (1998), 313-316  [abstract]

18.	Ch. Eslahchi, H. Hajiabolhassan, M.L. Mehrabadi and R. Tusserkani A counterexample for Hilton-Johnson's conjecture on list-coloring of graphs Australas. J. Combin. 18 (1998), 127-131  [abstract]

19.	S. Akbari, M. Behzad, H. Hajiabolhassan and E. S. Mahmoodian Uniquely total colorable graphs Graphs Combin. 13 (1997), 305-314  [abstract]

20.	S. Akbari-Feyzaabaadi, M. Mahdavi-Hezavehi, M. Mehraabaadi and H. Hajiabolhassan On derived groups of division rings II Comm. Algebra 23 (1995), 2881-2887  [abstract]