About Me
I'm a Post-Doctoral Fellow at the University of Waterloo, working on extremal and probabilistic combinatorics, and graph decompositions under the supervision of Prof. Luke Postle. I completed my PhD at UNSW Sydney in 2023, supervised by Anita Liebenau. Topics I have recently worked on include graph Ramsey theory, arithmetic Ramsey theory, extremal problems for hypergraphs, random graphs and finite geometry.
I also obtained in 2009 a Master in Statistics and Economics from the ENSAE, Paris, and I worked for about 10 years in consulting for insurance companies and financial institutions.
You may find a detailed CV here.
Research
My primary field of interest is extremal and probabilistic combinatorics. I am particularly interested in the application of probabilistic techniques to Ramsey theory problems. Coloring the edges or vertices of a large enough (hyper)graph tends to force the apparition of monochromatic subgraphs or sub-structures. Ramsey theory explores the sufficient and/or necessary conditions upon which this happens. I'm also interested in various aspects of extremal combinatorics (inducibility, Hamiltonicity, ...)
The up-to-date list of my research articles is on Google Scholar here. You can also check arXiv
Published
Odd-Ramsey numbers of complete bipartite graphs, 2025, with S.Boyadzhiyska, S.Das, K.Petrova, European Journal of Combinatorics.
Clustered Colouring of Graph Products, 2025, with R.Campbell, J.P.Gollin, D.Harvey, K.Hendrey, B.Mohar, Y.Tamitegama, J.Tan, D.Wood. Initiated at the Structural Graph Theory Downunder II workshop. Electronic Journal of Combinatorics.
A note on the minimum degree of minimal Ramsey graphs, 2025, with A.Bishnoi, The Australasian Journal of Combinatorics, vol 95. I, pp.65--69.
On the use of senders for asymmetric tuples of cliques in Ramsey theory, 2024, with S.Boyadzhiyska, Journal of Combinatorial Theory, Series B.
. On the minimum degree of minimal Ramsey graphs for cliques versus cycles, 2023, with A.Bishnoi, S.Boyadzhiyska, D.Clemens, P.Gupta and A.Liebenau. SIAM Journal on Discrete Mathematics.
The minimum degree of minimal Ramsey graphs for cliques, 2020, with A.Bishnoi and J.Bamberg. Bulletin of the London Mathematical Society.
Preprints
Ramsey with purple edges, with A.Liebenau, N.Taylor.
Erdős meets Nash-Williams, with M.Delcourt, C.Henderson, L.Postle.
Beyond Nash-Williams: Counterexamples to Clique Decomposition Thresholds for All Cliques Larger than Triangles, with M.Delcourt, C.Henderson, L.Postle.
Fractional Clique Decompositions of Dense Hypergraphs, with M.Delcourt, L.Postle.
Odd-Ramsey numbers of Hamilton cycles, with S.Boyadzhiyska, S.Das, K.Petrova,
PhD Thesis
On the use of senders for minimal Ramsey theory, 2023.
Master Thesis
Discrete duality principle in different random graph models, 2019.
Conferences and workshops
2025/09, Workshop on Finite Geometry and Ramsey Theory, Banff International Research Station, Canada.
2025/06, Combinatoric Seminar, Invited talk, UNSW Sydney, Australia. 'Refined Absorption and HighGirth Decompositions'.
2024/12, 46th Australasian Combinatorics Conference, Brisbane, Australia. Contributed talk, 'Odd-Ramsey numbers for complete bipartite graphs'.
2024/11, Tutte Colloquium, University of Waterloo, Invited talk, 'Odd-Ramsey numbers for complete bipartite graphs'.
2024/06, URA Seminar, University of Waterloo, Invited talk, ‘Beyond Ramsey numbers’.
2024/06, Graphs and Matroids Seminar, University of Waterloo, Invited talk, ‘Ramsey with purple edges’.
2023/12, 45th Australasian Combinatorics Conference, Perth, Australia
2023/12, Workshop on Extremal Problems in Graphs, Designs, and Geometries, Matrix research institute, Creswick, Australia.
2022/12, 44th Australasian Combinatorics Conference, Online. Contributed talk, 'On the use of senders in Ramsey theory'.
2022/12, 66th Annual Meeting of the Australian Mathematical Society, Sydney Australia. Contributed talk, 'On the use of senders in Ramsey theory'.
2022/09, Workshop of the Combinatorics and Graph Theory Research Group, FU Berlin, Berlin Germany.
2022/08, Random Structures and Algorithms, Gniezno Poland. Contributed talk, ‘Minimum degree of asymmetric Ramsey-minimal graphs’.
2022/07, Berlin Combinatorics research seminar, Berlin Germany. Invited talk, ‘Ramsey theory through group theoretic model of generalized quadrangles’.
2022/07, Prague Summer School on Discrete Mathematics, Prague Czech Republic.
2022/07, Discrete Mathematics Days 2022, Santander Spain. Participant.
2022/03, Structural Graph Theory Downunder II workshop, Matrix research institute, Creswick, Australia.
2021/12, 43rd Australasian Combinatorics Conference, Online. Contributed talk, ‘Minimum degree of asymmetric Ramsey-minimal graphs’.
2021/07, 28th British Combinatorial Conference, Online. Contributed talk, ‘Minimum degree of asymmetric Ramsey-minimal graphs’.
2021/07, Online workshop on positional games.
Organization
2024/01, Postdoc Engagement Liaison, University of Waterloo.
2022/09, UNSW Combinatorics Reading group, 'On threshold properties in random graphs and the Kahn-Kalai conjecture'
2022/05, Student Symposium in Combinatorics, A week long conference by students for students. 150 registrations, 50 contributed talks, 11 plenary speakers.
Contact
University of Waterloo, Department of Combinatorics and Optimization
200 University Ave West, Waterloo, ON N2L 3G1, Canada
Email: tlesgourgues at gmail.com