Towards Verified Construction for Planar Class of a Qualitative Spatial Representation
PLCA is a framework for qualitative spatial reasoning, using symbolic objects and relationships between them. To show construction of a PLCA expression, the second and the third authors introduced inductive constructions. They also proved that expressions obtained by inductive constructions are planar (planarity) and planar PLCA expressions can be obtained by inductive constructions (realizability). The former one is proven with Coq proof assistant, but the latter is proven with pen-and-paper.We are currently proving the latter with Coq. We locate some oversights in the original inductive constructions and the proof. In this paper, we report these oversights, re-formalization of inductive constructions and modified proofs. We prove planarity and a base case of realizability with Coq, and induction step of realizability with Coq and pen-and-paper proof.