Hovhannes A. Harutyunyan, Ph.D.

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 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 temporal graphs, social networks, and diagnosis of computer networks.

Selected Papers

Book Chapters

H. A. Harutyunyan, A. L. Liestman, J. Peters, D. Richards. Broadcasting and Gossiping. The Handbook of Graph Theory, J. Gross, Yellen, P. Zhang eds. Chapman and Hall/CRC, pp. 1477-1494, 2013.

R. Ahlswede, H.S. Haroutunian, L.H. Khachatrian. Messy Broadcasting in Networks. Communications and Cryptography, R.E. Blahut, D.G Costello, Jr. Maurer, T. Mittelholzer eds. Kluwer Academic, Boston/Dorrecht/London, pp. 13-24, 1994.

Journal Articles

H. A. Harutyunyan, Z. Li: New Construction of Broadcast Graphs. Discrete Applied Mathematics 280: 144-155 (2020).
P. Bhabak, H. A. Harutyunyan: Approximation Algorithms for the Broadcast time in k-Path Graph. Journal of Interconnection Networks 19(4): 1950006:1-1950006:22 (2019).
H. A. Harutyunyan, M. Terzian: Directional core selection approach and dynamic tree reorganization for delay and delay variation multicast routing. Int. J. Communication System 31(4) (2018).
H. A. Harutyunyan, S. Kamali: Efficient broadcast trees for weighted vertices. Discrete Applied Mathematics 216: 598-608 (2017).
P. Crescenzi, P. Fraigniaud, M. Halldorsson, H. A. Harutyunyan, C. Pierucci, A. Pietracaprina, G. Pucci: On the complexity of the shortest-path broadcast problem. Discrete Applied Mathematics 199: 101-109 (2016).
H. Grigoryan, H. A. Harutyunyan: The shortest path problem in the Knödel graph. Journal of Discrete Algorithms 31: 40-47 (2015).
H. Grigoryan, H. A. Harutyunyan: Diametral broadcast graphs. Discrete Applied Mathematics 171: 53-59 (2014).
H. Baumann, P. Fraigniaud, H. A. Harutyunyan, R. de Verclos. The worst case behavior of randomized gossip protocols. Theoretical Comp. Science 560: 108-120 (2014).
G. Barsky, H. Grigoryan, H. A. Harutyunyan: Tight lower bounds on broadcast function for n=24 and 25. Discrete Applied Mathematics 175: 109-114 (2014).
H. A. Harutyunyan, A. L. Liestman: Upper bounds on the broadcast function using minimum dominating sets. Discrete Mathematics 312(20): 2992-2996 (2012).
H. A. Harutyunyan, P. Hell, A. L. Liestman. Tight Upper Bounds on Messy Broadcast Time. Discrete Appliead Mathematics, vol. 159, Issue 5, pp. 322-327, 2011.
H. A. Harutyunyan, A. L. Liestman, K. Makino, T. Shermer. Non-adaptive Broadcasting in Trees. Networks, 57(2): 157-168 (2011).
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, E. Maraachlian. On Broadcasting in Unicyclic Graphs. Journal of Combinatorial Optimization, vol. 16, Issue 3, pp. 307-322, 2008.
H. A. Harutyunyan. An efficient vertex addition method for broadcast networks Internet Mathematics, vol. 5, No. 3, pp. 197-211, 2008.
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.

Refereed Conference Papers

P. Bhabak, H. A. Harutyunyan: Approximation Algorithms in Graphs with Known Broadcast Time of the Base Graph. CALDAM 2022: 305-316
S. Bakhtar, H A. Harutyunyan: Dynamic Local Community Detection Algorithms. NOMS 2022: 1-6
H. A. Harutyunyan, Z. Li: The Complexity of Finding a Broadcast Center. AAIM 2021: 57-70
S. Bakhtar, H. A. Harutyunyan: A New Fast Local Community Detection Algorithm Using the Number of Common Neighbours. SNAMS 2021: 1-8
H. A. Harutyunyan, D. Pankratov, J. Racicot: Online Domination: The Value of Getting to Know All your Neighbors. MFCS 2021: 57:1-57:21
M. S. Gholami, H. A. Harutyunyan: A Broadcasting Heuristic for Hypercube of Trees. CCWC 2021: 355-361
S. Bakhtar, M. S. Gholami, H. A. Harutyunyan: A New Metric to Evaluate Communities in Social Networks Using Geodesic Distance. CSoNet 2020: 202-216
N. Conlan, H. A. Harutyunyan, E. Maraachlian: Heuristic Algorithms with Near Optimal Broadcasting in Cactus Graphs. PDP 2020: 253-257
H. A. Harutyunyan, Z. Li: A Simple Construction of Broadcast Graphs. COCOON 2019: 240-253
H. A. Harutyunyan, M. Terzian: A Dynamic Multi-Core Multicast Approach for Delay and Delay Variation Multicast Routing. PDP 2018: 222-228
H. A. Harutyunyan, Z. Li: Broadcast Graphs Using New Dimensional Broadcast Schemes for Knödel Graphs. CALDAM 2017: 193-204
H. A. Harutyunyan, M. Terzian: A Multi-core Multicast Approach for Delay and Delay Variation Multicast Routing. HPCC/SmartCity/DSS 2017: 154-161
P. Bhabak, H. A. Harutyunyan, P. Kropf: Efficient Broadcasting Algorithm in Harary-like Networks. ICPP Workshops 2017: 162-170
H. A. Harutyunyan, Z. Li: Improved Lower Bound on Broadcast Function Based on Graph Partition. IWOCA 2017: 219-230
H. A. Harutyunyan, Z. Li: A New Construction of Broadcast Graphs. CALDAM 2016: 201-211
Hovhannes A. Harutyunyan, Meghrig Terzian: Directional Core Selection Approach for Delay and Delay Variation Multicast Routing. HPCC 2016: 481-488
H. A. Harutyunyan, M. Terzian: 3-Additive Approximation Algorithm for Multicast Time in 2D Torus Networks. ICA3PP 2016: 129-142
P. Bhabak, H. A. Harutyunyan: Constant Approximation for Broadcasting in k-cycle Graph. CALDAM 2015: 21-32
H. A. Harutyunyan, M. Terzian: Two Modified Multicast Algorithms for Two Dimensional Mesh and Torus Networks. PAAP 2015: 122-128
H. Grigoryan, H. A. Harutyunyan: New Lower Bounds on Broadcast Function. AAIM 2014: 174-184
H. A. Harutyunyan: Broadcast Networks with Near Optimal Cost. AAIM 2014: 312-322
H. A. Harutyunyan, C. Jimborean: New Heuristic for Message Broadcasting in Networks. AINA 2014: 517-524
S. C. Altay, H. A. Harutyunyan: New Properties for Broadcasting in KG2k. C3S2E 2014: 8
H. A. Harutyunyan, G. B. Oad: Exploring the diameter and broadcast time of general Knödel graphs using extensive simulations. C3S2E 2014: 25
P. Bhabak, H. A. Harutyunyan: Broadcast Problem in Hypercube of Trees. FAW 2014: 1-12
H. A. Harutyunyan, A. Malani: Efficient Multicast Algorithms for Mesh and Torus Networks. ISPA 2014: 231-236
P. Bhabak, H. A. Harutyunyan, S. Tanna: Broadcasting in Harary-Like Graphs. CSE 2014: 1269-1276
H. A. Harutyunyan, S. Wang: Two New Multicast Algorithms in 3D Mesh and Torus Networks. HPCC/CSS/ICESS 2014: 1150-1157
H. Grigoryan, H. A. Harutyunyan: Tight Bound on the Diameter of the Knödel Graph. IWOCA 2013: 206-215
H. Baumann, P. Fraigniaud, H. A. Harutyunyan, R. de Verclos: The Worst Case Behavior of Randomized Gossip. TAMC 2012: 330-345
H. A. Harutyunyan, S. Kamali. Optimal Broadcasting in Complete Weighted Vertex Graph. SOFSEM 2010: 489-502.
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, 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, Calin D. Morosan: The global fault-tolerance of interconnection networks. SNPD 2006: 171-176
H. A. Harutyunyan, P. Taslakian: Orderly Broadcasting in a 2D Torus. IV 2004: 370-375
H. A. Harutyunyan: Multiple message broadcasting in modified Knödel graph. SIROCCO 2000: 157-165
H. A. Harutyunyan and X. Xu. Minimum Broadcast Graph on 127 VerticesTechnical Report, Dep. of Computer Science, Concordia University, Montreal, QC, 2004.

Graduate Student Supervision
Current Graduate Students

Narek Hovhannisyan - Ph.D. since 2021 Fall.
Jesse Racicot (co-supervised with Dr. Pankratov) - Ph.D. since 2021 Summer.
Saber Gholami - Ph.D. since 2019 Fall.
Sahar Bakhtar - Ph.D. since 2019 Summer.
Aram Khanlari - MS since 2021 Fall.

Ph.D. Theses Supervised

Meghrig Terzian. On Near Optimal Time and Dynamic Delay and Delay Variation Multicast Algorithms. Ph.D. graduated in 2018, Concordia University
Zhiyuan Li. Improved Upper Bounds and Lower Bounds on Broadcast Function. Ph.D. graduated in 2018, Concordia University
Puspal Bhabak. Approximation Algorithms for Broadcasting in Simple Graphs with Intersecting Cycles. Ph.D. graduated in 2015, Concordia University
Hayk Grigoryan. Problems Related to Broadcasting in Graphs. Ph.D. graduated in 2013, Concordia University
Edward Maraachlian. Optimal Broadcasting in Treelike Graphs. Ph.D. graduated in 2010, Concordia University
Calin Dan Morosan. Studies of Interconnection Networks with Applications in Broadcasting. Ph.D. graduated in 2007, Concordia University
Bin Shao. On Optimal Broadcasting in Graphs. Ph.D. graduated in 2006, Concordia University

Master Theses Supervised

Aria Adibi Broadcasting in Hyper-Cylinder Graphs. Master’s thesis, Concordia University, 2021.
Anne-Laure Ehresmann Approximation Algorithms for Broadcasting in Flower Graps. Master’s thesis, Concordia University, 2021.
Jesse Racicot Domination : Offline, Online, Any Time (co-supervised with Dr. Pankratov). Master’s thesis, Concordia University, 2021.
Kamran Koupayi Separation and Cover Problems in Temporal Graph (co-supervised with Dr. Pankratov). Master’s thesis, Concordia University, 2020.
Shadi Taghian Exploring Temporal Cycles and Grids (co-supervised with Dr. Pankratov). Master’s thesis, Concordia University, 2020.
Neil Conlan Heuristic Algorithms For Broadcasting In Cactus Graphs. Master’s thesis, Concordia University, 2018.
Rakshit Majithiya Deeper Heuristic for Broadcasting in Networks. Master’s thesis, Concordia University, 2014.
Shreelekha Tanna Broadcasting in Harary Graphs. Master’s thesis, Concordia University, 2014.
Gul Bahar Oad Diameter and Broadcast Time of the Knödel graph. Master’s thesis, Concordia University, 2014.
Sirma Cagil Altay A general upper bound on broadcast function B(n) using Knodel graph. Master’s thesis, Concordia University, 2013.
Cosmin Jimborean: New Heuristic for Message Broadcasting in Networks. Master’s thesis, Concordia University, 2013.
Ankit Malani Efficient Multicast Algorithms for Mesh and Torus Networks. Master’s thesis, Concordia University, 2012.
Wei Wang Broadcsting via Shrotest Paths. Master’s thesis, Concordia University, 2011.
Georgy Barsky A Tight Lower Bounds on broadcast Function B(n). Master’s thesis, Concordia University, 2010.
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.


Teaching

  • COMP 232 Discrete Mathematics for Computer Science
  • COMP 335 Theoretical Computer Science
  • COMP 352 Data Structures and Algorithms
  • COMP 445 Data Communication and Computer Networks
  • COMP 465 Design and Analysis of Algorithms
  • COMP 6461 Computer Networks and Protocols
  • COMP 6651 Algorithm Design Techniques
  • COMP 6661 Combinatorial Algorithms
  • COMP 7241 Parallel Algorithms and Architectures
  • COMP 7651 Advanced Analysis of Algorithms


Service

Research - Graduate Program Director, Department of Computer Science and Software Engineering, Concordia University, January 2021 – July 2021

Undergraduate Program Director, Department of Computer Science and Software Engineering, Concordia University, July 2016 – July 2017

Research - Graduate Program Director, Department of Computer Science and Software Engineering, Concordia University, July 2012 – July 2013

Professor (tenure), Department of Computer Science and Software Engineering, Concordia University, May 2011 –

Research - Graduate Program Director, Department of Computer Science and Software Engineering, Concordia University, January 2009 – July 2009

Course - Graduate Program Director, Department of Computer Science and Software Engineering, Concordia University, June 2004 – June 2007

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

Associate Professor (tenure), Department of Computer Science, Concordia University, May 2004 – May 2011