Dealing with redundancy and inconsistency in constructive geometric constraint solving

General constructive geometric constraint solvers are pre-processed by a degree-of-freedom analysis, which enables efficient graph decomposition and recombination. However, all these methods are based on the assumption that structural rigidity automatically assures solvability. In this paper, we show that this assumption fails in numerous, even the most basic, configurations. We introduce several simple but efficient rules aimed to additionally analyse solvability in such cases. Another novelty addresses conditional constraints between three or more geometric parts, rules for their simplification and a redundancy check. All these functionalities are built into our original 2D geometric constraint solver, based on concepts of rigid clusters and constrained-angle (CA) sets.