Colourful Carath\'eodory's Theorem plus a constraint

We develop a topological framework in an attempt to generalize the classical colourful Caratheodory theorem by imposing an additional constraint. For that we introduce the notion of zero-avoding complexes and covering criteria for the existence of colourful transversals. Using the developed method in combination with the homological Nerve theorem of Meshulam we recover all known versions of the colourful Caratheodory's theorem and prove a constraint extension which, in particular, implies an extension of the original (affine) Tverberg result.