Suppose we are given four angles $$\alpha$$, $$\beta$$, $$\gamma$$ and $$\delta$$. For a quadrilateral to exist with interior angles $$\alpha$$, $$\beta$$, $$\gamma$$ and $$\delta$$ in the hyperbolic plane we must have $$\alpha +\beta+\gamma+\delta< 2\pi$$. But what are the sufficient conditions for the existence of a hyperbolic quadrilateral with interior angles $$\alpha$$, $$\beta$$, $$\gamma$$ and $$\delta$$ satisfying $$\alpha +\beta+\gamma+\delta< 2\pi$$?