The 4-choosability of toroidal graphs without intersecting triangles

In this paper we prove that every toroidal graph without two triangles sharing a common vertex is 4-choosable. This generalizes a result by Wang and Lih [W. Wang, K.-W. Lih, Choosability and edge choosability of planar graphs without intersecting triangles, SIAM J. Discrete Math. 15 (2002) 538–545], which says that every planar graph without triangles sharing a common vertex is 4-choosable.