We generalize Quillen's Theorem A to triangles of lax 2-functors which commute up to transformation. It follows from a special case of this result that 2-categories are models for homotopy types.
Keywords: homotopy theory, 2-categories, Quillen's Theorem A
2010 MSC: 18D05, 18G55, 55U35
Theory and Applications of Categories, Vol. 30, 2015, No. 4, pp 49-85.