Combinatorics is the study of discrete, as opposed to continuous, structures. The subject goes back to antiquity, and is often associated with counting of objects, but has developed into a tool to study discrete structures that appear throughout mathematics. The study of such connections is ancient on its own, with regular convex polyhedra already being carved out of stone in the neolithic era and often conflated with religious mysticism, but already observing the connection between the discrete, geometry and symmetry. At the Hebrew University in particular, combinatorics has a distinct interdisciplinary flavor, with researchers investigating it in connection to dynamics, representation theory, analysis, probability, geometry, algebra, computer science and physics.

Faculty members in Combinatorics:

- Karim Adiprasito: Relations between combinatorics, algebra, topology and geometry.
- Gil Kalai (emeritus): Convexity, Combinatorics.
- David Kazhdan: Representation theory, combnatorics.
- Nati Linial: Combinatorics, The Theory of Algorithms, Applications of Geometry and Analysis to the above fields, Computational Molecular Biology.
- Alex Lubotzky: Group theory, Lie groups, Field arithmetic, Algebraic groups, Discrete subgroups of Lie groups, Combinatorics, Representation theory.
- Eran Nevo: Combinatorics with connections to commutative algebra, topology, geometry and convexity.
- Ohad Noy Feldheim: Probability Theory, Combinatorics and Mathematical Physics.
- Ori Parzanchevski: Group theory, Representation theory, Combinatorics.
- Micha Perles (emeritus): Convexity, Combinatorial geometry, Combinatorics, Graph theory.
- Eli Shamir (emeritus): Random structures, Analysis of algorithms, Differential equations.
- Tamar Ziegler: Ergodic theory, Number theory, Combinatorics.