Block Intersection Theorem for Symmetric Designs Combinatorics König's Theorem Logic Matroid Union Theorem Combinatorics Frame-Robinson-Thrall Hook-Length Formula Combinatorics Excluded-Minor Characterisation of Minor-Closed Matroid Classes Discrete Mathematics Matroid Base Polytope Inequality Description Discrete Mathematics Planar Duality for Graphic Matroids Discrete Mathematics Ruzsa Covering Lemma Combinatorics Discrete Mathematics Area