a)Visited Hungary under the Indo-Hungarian Cultural Exchange Programme of UGC and gave lectures at the Mathematical Research Institute of Hungarian Academy of Sciences and Eotvos Lorand University, Budapest, Hungary.,October 1994 .
b)Participated in the ‘School and Workshop on Approximate Solutions of Hard Combinatorial Problems’ held at the International Centre for Mechanical Sciences, Udine, Italy during 10-19, September 1996.
c)Visited the Universities of Manitoba, New Brunswick, Newfoundland and Waterloo, Canada during April - July 1999 for collaborative research and lectures.
d)Invited talk on ‘Graph Convexity Spaces- Combinatorial Aspects’ AARMS Combinatorics Workshop, Memorial University of Newfoundland, Canada, May 24-28, 1999.
e)Invited Talk on ‘Brun's Property for Graph Convexity Spaces’ Summer Meeting of the Canadian Mathematical Society, Memorial University of Newfoundland, Canada, May 29- June 1, 1999.
f)Visiting Scientist at the Indian Statistical Institute, Kolkata during July-September, 2004 (during Sabbatical leave).
g)Contributed talk in the joint International Conference of Taiwan Mathematical Society and American Mathematical Society, Tunghai University, Taiwan , 14-18, December 2005.
h)Presented a contributed paper ‘Reciprocal Graphs’ in the International Congress of Mathematicians (ICM), Madrid, Spain, August 22 - 30, 2006.
i)Visiting Professor, Simon Fraser University, Canada, May - June 2007.
j)Presented a paper ‘Teaching and Learning of Discrete Mathematics- Indian Scenario’ TSG-15 of the International Congress on Mathematics Education (ICME -11), Monterrey, Mexico, July 6-13, 2008.
k)Invited Talk on ‘ Clique irreducible and weakly clique irreducible graphs-A Survey’ in the First India- Taiwan Conference on Discrete Mathematics , National Taiwan University, Taipei, Taiwan, November 9-12, 2009.
l)Visiting Professor, Department of Applied Mathematics and Institute for Theoretical Computer Science, Charles University, Prague , Czech Republic , August 2011.
m)Talk on ‘Graph Operators and Its Dynamics - Some Recent Studies’, Department of Applied Mathematics and Institute for Theoretical Computer Science, Charles University, Prague, Czech Republic , 18th August 2011.
n)‘Excitements and Applications of Mathematics’, Interactive session with students of International School, Prague, Czech Republic , 22nd August 2011.
o)Presented a paper ‘ Power domination in some classes of Graphs’ , Eurocomb-11, Eotvos Lorand university and Alfred Renyi Institute, Budapest, Hungary,29 August-2 September, 2011.
p)Participated as a Member of the Indian delegation, in the International Congress on Mathematical Education (ICME-12) ,Seoul, S.Korea during 8-15th July 2012.
q)Invited Talk in the Instructional workshop on Graph Theory and Interconnection Networks, Tunghai University, Taichung, Taiwan, 15-16, November, 2013.
r)Invited Talk in the Third India-Taiwan Conference on Discrete Mathematics, National Chiao Tung University, Hsinchu, Taiwan, 18-22 November, 2013.
s)Participated in the International Symposium on Mathematics for Emerging Nations Achievements and Opportunities (MENAO) at Seoul, S.Korea on 13 August 2014 organised by International Mathematical Union(IMU).
t)Presented a contributed paper ‘Bondage number of product graphs’ International Congress of Mathematicians (ICM), Seoul, S.Korea, August 13 – 21, 2014.
u)Invited talk on’ Mathematics to the Masses - Some Success Stories from India’, International Congress on Mathematics Education, Hamburg, Germany, July 24-31, 2016.
v)Invited talk on ‘Power domination in graph products’ 5th India- Taiwan Conference on Discrete Mathematics, Tamkang University, Taiwan, 18-21 July 2017.
w)Invited talk on ‘Distance Spectra of Some Graph Classes- A Survey , 9th Slovenian International Conference on Graph Theory , Bled, Slovenia, 23-30 June 2019.
a)‘Graph Energy’, 25th Kerala Science Congress, Trivandrum, 30 January 2013.
b)‘Iterations of Line Graphs and Its dynamics’, Research Promotion Workshop on Introduction to Graph and Geometric Algorithms, TIFR-IIITMK-Kerala University, 25th January 2014.
c)‘Spectra and energy of graphs’ and ‘Shrikhande graph’, UGC workshop on ‘Zeta function for graphs’, S P University, Pune ,11-13 November 2014.
d)Invited talk in the Conference on Creative Mathematical Sciences Communications, The Institute of Mathematical Sciences, Chennai. 9-12 December 2014.
e) ‘Generalized power domination problem’ Fourth India - Taiwan Conference on Discrete Mathematics, IIT Madras, July 10-13, 2015.
f)Power Domination Problem, International Conference in Mathematics, Kerala University, November 26-28, 2015.
g)Invited talk in the National Seminar on Information Theory and Communication, (100th birth Anniversary of Shannon) , Rajagiri School of Engineering and Technology, Cochin , 30th April 2016.
h)Invited talk in the Special Symposium on Mathematics Education , 31st Annual Conference of Ramanujan Mathematical Society, Tiruchirappally, India, June 18-21, 2016.
i)The Power Domination Problem in Graphs, International Conference on Theoretical Computer Science and Discrete Mathematics , Kalasalingam University, Krishnankoil, December 19-21, 2016.
j)‘What is happening in Mathematical Sciences ‘ Lead lecture in the Mathematical and Statistical Sciences Session, 29th Kerala Science Congress, Marthoma College, Thiruvalla. January 29, 2017.
k)Resource Person, Azim Premji University- Ramanujan Math. Society Workshop for School Teachers, Chinmaya Vidyalaya , Kannur, May 2017.
l)‘Median Problems in Graphs ‘ International Conference in Graph Theory and Networks, St.Xaviers College, Aluva, October30- November1, 2017.
m)Some Network Topological Notions of the Mycielskian of a Graph, International Conference on Discrete Mathematics and its Applications to NetworkScience, BITS Goa, July 7-10,2018.
n)Key Note Speaker, The changing face of Mathematics, National Level Workshop On Discovering the Art of Mathematics, Department of Mathematics, University of Kerala, 18th December 2018.
o)‘Excitements in Mathematics’ Lead Lecture in the Mathematical and Statistical Sciences Session , 31st Kerala Science Congress, Fatima Matha National college, Quilon, February 3, 2019.
p)Invited talk on Graph Operators and its Dynamics, International Conference on Graphs and Combinatorics, Mangalore University, 1-2 December 2022.
q)Key Note Address , From Bridges to Brain networks , International Conference on Number Theory and Graph Theory, Manipal Institute of Technology, Manipal.18-20 January 2023.
r)Platinum Jubilee Public Lecture, Government College , Chittur-Palghat,’ Relevance of Mathematics in the Information age’,16 February 2023
s)Invited talk on ‘Evolution of Real World Networks, International Conference on Recent Trends in Applied Mathematics, FISAT, Angamaly, 24th February 2023.
t)Professor E.Sampathkumar Endowment Lecture, International Conference in Discrete Mathematics, Mysore, June 8-10,2023.
📝Have spread the message of ‘Break The Chain’ through these webinars to more than ten thousand students/teachers
Hundredth death anniversary of Srinivasa Ramanujan , St.Xaviers College, Alwaye., St.Pauls college, Kalamassery-26/4/2020
International FDP on Recent Trends in Graph theory, MES College, Mampad, - 20/5/2020
International Conference on Algebra and Discrete Mathematics, Madurai Kamaraj University - 24/6/2020
International Webinar on Recent Trends in Mathematics and its Applications, JNU, New Delhi – 23/7/2020
5th Dr.APJ Abdul Kalam Memorial Lecture, St.Pauls College, Kalamassery-27/7/2020.
FDP - Mathematics for Data Sciences, MITS, Ernakulam - 11/8/2020
New York University Combinatorics Seminar -23/10/2020
National Mathematics Day Lecture- KSCSTE , Jammu University -22/12/2020
Discrete Mathematics Seminar, Simon Fraser University, Canada- 27/1/2021
FOCUS- Multi disciplinary Webinar Series, S N College, Kannur - 22/3/2021
KTU-FDP on Mathematical Foundations for AI and ML , MITS Ernakulam- 24/6/2021
FDP- Recent Trends in Mathematics- Amrita School of Arts and Sciences, Cochin-6/7/2021
National Symposium on Challenges and Applications of Mathematics, SVKM Group of Institutions, Mumbai – 17/7/2021
International Workshop on Graph Domination, St.Pauls College,Kalamassery -20/7/2021
Webinar on Dr.APJ Abdul Kalam,NSS Unit, MITS,Ernakulam-7/8/2021
International Webinar in Honour of Laslo Lovasz, CUSAT, 22/11/2021
Keynote Address , International Workshop on Graphs from Algebraic Structures, M S University, Tirunelveli. 7/10/2021
International Conference on Theoretical Computer Science and Discrete Mathematics, SSN College of Engineering, Chennai. 2/12/2021
National Mathematics Day Lectures at Sree Ramakrishna College, Coimbatore; School of Sciences , IGNOU, New Delhi; S H College, Thevara, Cochin; BCM College, Kottayam ,22/12/2021
International Conference on Graphs, Combinatorics and Optimization, BITS, Dubai Campus, 7/2/2022.
Memorial Lecture of Dr. APJ Abdul Kalam organized for Bharathiya Vidya Bhavan Schools- 27/7/2022.
City University of New York, USA - NYCS- 14/10/2022
University of Applied Sciences and Technology, Muscat, Sultanate of Oman-20/10/2022.
Dr. A P J Abdul Kalam memorial lecture, SCMS Group of Institutions, 27/7/2023.