Stephan Wagner

My research interests are mainly in discrete mathematics, especially combinatorial probability (random trees, random graphs and other random structures), enumerative and analytic combinatorics, and graph theory.

2000 - 2006 Studies in mathematics at TU Graz, Austria

2007 - 2019 Department of Mathematical Sciences, Stellenbosch University, South Africa

2020 - current Department of Mathematics, Uppsala University

Recent publications and preprints:

2020

• On the minimal Hamming weight of a multi-base representation, Journal of Number Theory 208 (2020), 168-179; with D. Krenn and V. Suppakitpaisarn. Preprint: [pdf]
• Inducibility of d-ary trees, Discrete Mathematics 343/2 (2020), 111671 (15 pages); with E. Czabarka, A. A. V. Dossou-Olory and L. Székely. Preprint: [pdf]
• A central limit theorem for almost local additive tree functionals, Algorithmica 82/3 (2020), 642-679; with D. Ralaivaosaona and M. Šileikis. Preprint: [pdf]
• On the distance spectral radius of trees with given degree sequence; Discussiones Mathematicae Graph Theory 40/2 (2020), 495-524; with K. Dadedzi and V. Razanajatovo Misanantenaina.
• On the number of increasing trees with label repetitions, Discrete Mathematics 343/8 (2020), 111722 (12 pages); with O. Bodini, A. Genitrini and B. Gittenberger. Preprint: [pdf]
• The average size of independent sets of graphs, European Journal of Mathematics 6 (2020), 561-576; with E. O. D. Andriantiana and V. Razanajatovo Misanantenaina. Preprint: [pdf]
• The average size of matchings in graphs, Graphs and Combinatorics 36 (2020), 539-560; with E. O. D. Andriantiana and V. Razanajatovo Misanantenaina. Preprint: [pdf]
• Matchings in graphs with a given number of cuts, Discrete Applied Mathematics 283 (2020), 473-481; with J. Liu and F. Huang. Preprint: [pdf]
• Block statistics in subcritical graph classes, Proceedings of the 31st International Conference on Probabilistic, Combinatorial and Asymptotic Methods for the Analysis of Algorithms (AofA 2020); Leibniz International Proceedings in Informatics 159, Article 24; with C. Requilé and D. Ralaivaosaona.
• On the probability that a random digraph is acyclic, Proceedings of the 31st International Conference on Probabilistic, Combinatorial and Asymptotic Methods for the Analysis of Algorithms (AofA 2020); Leibniz International Proceedings in Informatics 159, Article 25; with D. Ralaivaosaona and V. Rasendrahasina.
• On the Collection of Fringe Subtrees in Random Binary Trees, Proceedings of the 14th Latin American Theoretical Informatics Symposium (LATIN 2020), São Paulo, Brazil; Lecture Notes in Computer Science 12118 (2020), 546-558; with L. Seelbach Benkner. Preprint: [pdf]
• The number of distinct adjacent pairs in geometrically distributed words, Discrete Mathematics and Theoretical Computer Science 22/4 (2020), #10 (18 pages); with M. Archibald, A. Blecher, C. Brennan, A. Knopfmacher and M. D. Ward.
• On two subclasses of Motzkin paths and their relation to ternary trees, in Algorithmic Combinatorics - Enumerative Combinatorics, Special Functions and Computer Algebra (V. Pillwein and C. Schneider, eds.), Springer 2020; with H. Prodinger and S. Selkirk. Preprint: [pdf]

2021

• Irrationality of growth constants associated with polynomial recursions, Journal of Integer Sequences 24/1 (2021), article 21.1.6 (9 pages); with V. Ziegler.
• Extremal trees with fixed degree sequence, Electronic Journal of Combinatorics 28/1 (2021), P 1.1 (34 pages); with E. O. D. Andriantiana and V. Razanajatovo Misanantenaina.
• On the maximum mean subtree order of trees, European Journal of Combinatorics 97 (2021), 103388 (19 pages); with S. Cambie and H. Wang. Preprint: [pdf]
• Further results on the inducibility of d-ary trees. Australasian Journal of Combinatorics 81 (2021), 1-24; with A. A. V. Dossou-Olory.
• On the probability that a random subtree is spanning. Journal of Graph Theory 98/2 (2021), 195-215. Preprint: [pdf]

2022

• Trees with minimum number of infima closed sets. Discrete Mathematics 345/5 (2022), 112793 (20 pages); with E. O. D. Andriantiana. Preprint: [pdf]
• Trees in Many Contexts. Notices of the American Mathematical Society 69/2 (2022), 284-286; with H. Smith Blake, M. Bóna, E. Czabarka and H. Wang.
• Steiner Wiener index and line graphs of trees. Discrete Mathematics Letters (special issue dedicated to the memory of Nenad Trinajstić) 9 (2022), 86-91; with M. Kovše and V. Razanajatovo Misanantenaina.
• A polynomial associated with rooted trees and specific posets, Transactions on Combinatorics 11/3 (2022), 255-279; with V. Razanajatovo Misanantenaina.
• Uncovering a random tree. 33rd International Conference on Probabilistic, Combinatorial and Asymptotic Methods for the Analysis of Algorithms, Art. No. 10, 17 pp., LIPIcs. Leibniz Int. Proc. Inform., 225; with B. Hackl and A. Panholzer.
• Automorphisms of random trees. 33rd International Conference on Probabilistic, Combinatorial and Asymptotic Methods for the Analysis of Algorithms, Art. No. 16, 16 pp., LIPIcs. Leibniz Int. Proc. Inform., 225; with C. Olsson.
• Maximum number of subtrees in cacti and block graphs. Aequationes Math. 96/5 (2022), 1027-1040; with J. Li, K. Xu, T. Zhang and H. Wang.
• Gini index on generalized r-partitions. Math. Slovaca 72/5 (2022), 1129-1144; with T. Mansour, M. Schork and M. Shattuck.
• Distinct Fringe Subtrees in Random Trees, Algorithmica 84 (2022), no. 12, 3686–3728 ; with L. Seelbach Benkner. Preprint: [pdf]

2023

• On the mean subtree order of trees under edge contraction, Journal of Graph Theory 102/3 (2023), 535-551; with Z. Luo, K. Xu and H. Wang.
• Enumeration of Generalized Dyck Paths Based on the Height of Down-Steps Modulo k. Electronic Journal of Combinatorics 30/1 (2023), P1.26 (18 pages); with C. Heuberger and S. J. Selkirk.

• Broadcasting induced colourings of random recursive trees and preferential attachment trees, to appear in Random Structures & Algorithms; with C. Desmarais and C. Holmgren. Preprint: [pdf]
• Refined enumeration of k-plane trees and k-noncrossing trees, to appear in Annals of Combinatorics; with I. O. Okoth. Preprint: [pdf]

Preprints

• Limits of subcritical random graphs and random graphs with excluded minors; with A. Georgakopoulos. Preprint: [pdf]
• The birth of the strong components; with É. de Panafieu, S. Dovgal, D. Ralaivaosaona and V. Rasendrahasina. Preprint: [pdf]
• Convex characters, algorithms and matchings; with S. Kelk and R. Meuwese. Preprint: [pdf]
• Average Case Analysis of Leaf-Centric Binary Tree Sources; with M. Lohrey and L. Seelbach Benkner. Preprint: [pdf]
• On the distribution of eigenvalues of increasing trees; with K. Dadedzi. Preprint: [pdf]
• Trees maximizing the number of almost-perfect matchings; with S. Cambie, B. McCoy, G. Sharma and C. Yap. Preprint: [pdf]
• The minimum number of maximal independent sets in twin-free graphs; with S. Cambie. Preprint: [pdf]
• The distribution of the number of automorphisms of random trees; with C. Olsson. Preprint: [pdf]
• Conditioned Galton-Watson trees: The shape functional, and more on the sum of powers of subtree sizes; with J. A. Fill and S. Janson. Preprint: [pdf]
• The Uncover Process for Random Labeled Trees; with B. Hackl and A. Panholzer. Preprint: [pdf]

Older publications (before 2020) can be found here: Old publications