Detecting minors in matroids through triangles
  In this note we investigate some matroid minor structure results. In particular, we present sufficient conditions, in terms of {\em triangles}, for a matroid to have either $U_{2,4}$ or $F_7$ or $M(K_5)$ as a minor. 
Boris Albar, Daniel Gon\c{c}alves, Jorge L. Ram\'irez Alfons\'in
math.CO