ProGS: Property Graph Shapes Language

Knowledge graphs such as Wikidata are created by a diversity of contributors and range sources leaving them prone to two types errors. The first type error, falsity facts, is addressed property through the representation provenance validity, making triples occur first-order objects in subject position metadata triples. second violation domain constraints, has not been with regard so far. In RDF representations, this error can be shape languages SHACL or ShEx, which allow for checking whether valid respect set constraints. Borrowing ideas from syntax semantics definitions SHACL, we design language graphs, ProGS, allows formulating constraints on including their specific constructs, edges identities key-value annotations both nodes edges. We define formal investigate resulting complexity validating against sets ProGS shapes, compare corresponding results implement prototypical validator that utilizes answer programming.