Hovhannes A. Harutyunyan, Ph.D.

Associate Professor
Department of Computer Science and Software Engineering
Concordia University
Montreal, QC, H3G 1M8, Canada
Tel: (514) 848-2424 ext. 7804
Email: haruty@cs.concordia.ca

Research

The main area of my research is focused on the effect of network structure on network communications for parallel and distributed computing. Research in this direction includes the design of "good" interconnection network topologies and the investigation of information dissemination on various networks. The efficiency of communication in networks is very much depends on the interconnection structure of a network. Fully (or almost fully) connected networks are reliable and allow short communication paths. However, sparser networks may be more feasible to build while still providing reasonably efficient and reliable communications. Information dissemination problems in interconnection networks concern transmitting messages from a set of senders to a set of receivers within a network. Specific information dissemination processes are defined by placing constraints on the sets of messages, senders, and receivers, on the network's topology, on the rules that govern message transmissions, and on the amount of information about the network known to individual network members. One goal of research in this area is to design network structures which are inexpensive to construct yet allow efficient communication. An example of this work is the ongoing search for minimum broadcast graphs - the graphs with the fewest edges (for a fixed number of vertices) in which each vertex can broadcast in minimum time. A second major goal is to determine the communication times of commonly used network topologies under different communication models. Research in these areas requires knowledge of data communication and network protocols, techniques of graph theory, combinatorics, and design and analysis of algorithms. Other areas of my research include error-correcting codes, cryptography and diagnosis of computer networks.

Selected Papers

H. A. Harutyunyan, P. Hell, A. L. Liestman. Upper Bounds on Messy Broadcast Time Discrete Appliead Mathematics, submitted in 2009.
H. A. Harutyunyan, A. L. Liestman, K. Makino, T. Shermer. Non-adaptive Broadcasting in Trees. Networks, submitted in 2009.
H. A. Harutyunyan. An efficient vertex addition method for broadcast networks Internet Mathematics, vol. 5, No. 3, pp. 197-211, 2009.
H. A. Harutyunyan, A. L. Liestman and B. Shao. A Linear Algorithm for Finding the k-Broadcast Center of a Tree Networks, vol. 53, Issue 3, pp. 287 - 292, 2009.
H. A. Harutyunyan, S. Kamali. Optimal Broadcasting in Complete Weighted Vertex Graph. SOFSEM 2009
H. A. Harutyunyan, E. Maraachlian. Optimal Broadcasting in Fully-Connected Trees. ICPADS 2009.
H. A. Harutyunyan, R. Katragadda, C. D. Morosan. Efficient Heuristic for Multicasting in Arbitrary Networks. AINA 2009: 61-66.
H. A. Harutyunyan, E. Maraachlian. Linear Algorithm for Broadcasting in Networks With No Intersecting Cycles. PDPTA 2009: 296-301.
H. A. Harutyunyan, G. Laza, E. Maraachlian. Broadcasting in Necklace Graphs. C3S2E 2009: 253-256.
H. A. Harutyunyan, E. Maraachlian. On Broadcasting in Unicyclic Graphs. Journal of Combinatorial Optimization, vol. 16, Issue 3, pp. 307-322, 2008.
H. A. Harutyunyan, S. Kamali, T. Moradian. Multi-Shared-Trees Based Multicasting in Mesh-Connected Networks. PDPTA 2008: Vol. 1, 178-182.
H. A. Harutyunyan, E. Maraachlian. Near Optimal Broadcasting in Optimal Triple Loop Graphs. AINA 2008: 227-233.
H. A. Harutyunyan, S. Kamali. Efficient Broadcasting in Networks with Weighted Nodes. ICPADS 2008: 879-884.
H. A. Harutyunyan, S. Kamali. Broadcasting in Weighted Vertex Graphs. ISPA 2008: 301-307.
H. A. Harutyunyan, E. Maraachlian. Linear Algorithm for Broadcasting in Unicyclic Graphs. COCOON 2007: 372-382.
H. A. Harutyunyan, X. Xu. New Construction of Broardcast Graphs. IV 2007: 751-756.
H. A. Harutyunyan, C. D. Morosan, Y. Zhang. Two Tree-Based Algorithms for Network Spare Capacity Design. PDCAT 2007: 279-284.
H. A. Harutyunyan, J. He. A New Peer-to-Peer Network. PerCom Workshops 2007: 120-125.
H. A. Harutyunyan, B. Shao. Efficient heuristics for message dissemination in networks. Parallel and Distributed Computing and Networks 2007: 192-197.
H. A. Harutyunyan, S. Wang. Path-based multicasting in multicomputers. Parallel and Distributed Computing and Networks 2007: 206-211.
H. A. Harutyunyan and C. D. Morosan. On the Minimum Path Problem in Knodel Graphs, Networks, vol. 50, Issue 1, pp. 86-91, 2007.
H. A. Harutyunyan. Minimum Multiple Message Broadcast Graphs, Networks, vol. 47, Issue 4, pp. 218-224, 2006.
H. A. Harutyunyan and B. Shao. An Efficient Heuristic for Broadcasting in Networks, Journal of Parallel and Distributed Systems, vol. 66, Issue 1, pp. 68-76, 2006.
H. A. Harutyunyan and C. D. Morosan. The spectrum of Knodel Graphs, International Journal of Computing and Informatics, vol. 30, Issue 3, pp. 295-299, 2006.
H. A. Harutyunyan and A. L. Liestman. On the Monotonicity of Broadcast Function, Discrete Mathematics, vol. 262, Issue 1, pp. 140-157, 2003.
F. Comellas, H. A. Harutyunyan and A. L. Liestman. Messy Broadcasting in Mesh and Torus Networks, Journal of Interconnection Networks, vol. 4, pp. 37-51, 2003.
H. A. Harutyunyan and A. L. Liestman. k-Broadcasting in Trees, Networks, vol. 38, pp. 163-168, 2001.
H. A. Harutyunyan and A. L. Liestman. Improved Upper and Lower Bounds for k-Broadcasting. Networks, vol. 37, pp. 94-101, 2001.
H. A. Harutyunyan and A. L. Liestman. More Broadcast graphs. Discrete Applied Mathematics, vol. 98, no. 1-2, pp. 81-102, 1999.
H. A. Harutyunyan and A. L. Liestman. Messy Broadcasting. Parallel Processing Letters, vol. 8, no. 2, pp. 149-159, 1998.
J. –C. Bermond, H. A. Harutyunyan, A. L. Liestman and S. Perennes. A note on Dimensionality of modified Knödel graphs. International Journal of Foundations of Computing Science, vol. 8, no. 2, pp. 109-116, 1997.
H. A. Harutyunyan and X. Xu. Minimum Broadcast Graph on 127 VerticesTechnical Report, Dep. of Computer Science, Concordia University, Montreal, QC, 2004.
H. A. Harutyunyan, E. Maraachlian. Broadcasting in Fully Connected Trees, Performance Modelling and Analysis of Communication in Wired and Wireless Networks, PMAC-2WN'09, 2009.

Ph.D. Theses Supervised

Calin Dan Morosan. Studies of Interconnection Networks with Applications in Broadcasting. Ph.D. Thesis, Concordia University, 2007.
Bin Shao. On Optimal Broadcasting in Graphs. Ph.D. Thesis, Concordia University, 2006.

Master Theses Supervised

Shahin Kamali Efficient Broadcasting in Networks with Weighted Nodes. Master’s thesis, Concordia University, 2008.
Rahul Katraganda A Heuristic for Multicasting in Networks. Master’s thesis, Concordia University, 2008.
Talin Moradian Group Multicasting in Mesh-Connected Networks. Master’s thesis, Concordia University, 2008.
Junlei He Peer-to-peer Network Based on the Knödel Graph. Master’s thesis, Concordia University, 2007.
Guo Tai Chen An Algorithm for Gossiping and Broadcasting. Master’s thesis, Concordia University, 2006.
Edward Marachlian A Study of Multiloop Networks. Master’s thesis, Concordia University, 2006.
Yu Ying The Use of BES for the Cryptanalysis of AES. Master’s thesis, Concordia University, 2005.
Shengjian Wang Efficient Multicast Routing Algorithms in Mesh-connected Multicomputers. Master’s thesis, Concordia University, 2005.
Gurudath Subbana Generation of Programm Synchronization (co-supervised with Dr. Li). Master’s thesis, Concordia University, 2005.
Tejas Vyas A Differential Fault Attack for AES. Master’s thesis, Concordia University, 2004.
Perouz Taslakian Orderly Broadcasting in Torus (co-supervised with Dr. Fevens). Master’s thesis, Concordia University, 2004.
Yunzan Zhang. New Path Restoration Algorithms in Networks. Master’s thesis, Concordia University, 2004.
Calin Dan Morosan. New Communication Properties of Knodel Graphs. Master’s thesis, Concordia University, 2004.
Xiang Xu. Broadcast Networks of Odd Size and Minimum Broadcast Network on 127 Nodes. Master’s thesis, Concordia University, 2003.
Bin Shao. A New Heuristic for Broadcasting in Networks. Master’s thesis, Concordia University, 2003.
Xiaobo Dong. A New Algorithm for RP Selection in PIM-SM Multicast Routing. Master’s thesis, Concordia University, 2002.
Xiaolin Liu. On Multicast Algorithms in Mesh-connected Networks. Master’s thesis, Concordia University, 2002.

Current Graduate Students

Edward Maraachlian - Ph.D. since 2006 Summer.
Hayk Grigoryan - Ph.D. since 2009 Fall.
Georgy Barsky - MS since 2009 Winter.
Wei Wang - MS since 2009 Winter.

Teaching

Winter 2004: COMP 352 Data Structures and Algorithms (course coordinator)
Winter 2004: COMP 445 Data Communication and Computer Networks
Summer 2003: COMP 6461 Computer Networks and Protocols (coordinator)
Winter 2003: COMP 352 Data Structures and Algorithms
Winter 2003: COMP 6661 Combinatorial Algorithms
Fall 2002: COMP 335 Theoretical Computer Science
Fall 2002: COMP 6461 Computer Networks and Protocols (course coordinator)
Winter 2002: COMP 352 Data Structures and Algorithms
Fall 2001: COMP 335 Theoretical Computer Science
Fall 2001: COMP 6461 Computer Networks and Protocols

Service

Research - Graduate Program Director, Department of Computer Science, Concordia University, January 2009 - July 2009

Course Graduate Program Director, Department of Computer Science, Concordia University, June 2004 - June 2007

Graduate Diploma Program Director, Department of Computer Science, Concordia University, December of 2002 – May of 2003.

Member of Diploma Advisory Committee, Department of Computer Science, Concordia University, July 2001 – June 2004