RPQlike

RPQlike is a term used in graph query research to describe a family of query formalisms that generalize or extend Regular Path Queries (RPQ). It denotes approaches that aim to express and evaluate path constraints in labeled directed graphs with greater expressivity than standard RPQ, while preserving automata-based evaluation techniques. There is no single standard definition, but the concept appears in scholarly discussions and prototype systems as a way to explore richer path reasoning on knowledge graphs, social networks, and other graph-structured data.

Formally, RPQlike notions operate on a graph whose edges carry labels from an alphabet. A query consists of an expression built from regular operations such as concatenation, union, and Kleene star, possibly augmented with additional features like inverse edges, containment constraints, or simple data filters. The semantics typically require finding pairs of nodes connected by at least one path whose sequence of edge labels satisfies the RPQlike expression. In this sense, RPQlike subsumes RPQ and aspires to cover more complex path properties without abandoning the automata-driven evaluation paradigm.

In practice, RPQlike expressions are often compiled into finite automata and evaluated via a product construction with the input graph, enabling efficient query processing for fixed expressions. Extensions under the RPQlike umbrella may include two-way navigation, context-free path constraints, or path-length and resource-bounded constraints, reflecting ongoing research directions.

Related concepts include standard RPQ, context-free path queries, and SPARQL property paths. RPQlike remains a descriptive label rather than a single, widely adopted formalism, used to discuss potential enhancements to path querying in graph databases.