formaliser

A formaliser is a person, tool, or process that converts informal descriptions into formal representations using a formal language. The aim is to remove ambiguity and enable rigorous analysis, verification, or automatic reasoning. In practice, the term is used in mathematics, computer science, and knowledge engineering. The spelling formaliser is common in British English; formalizer is the American variant.

Formalisation is applied in various domains: formal mathematics, where proofs are expressed in a formal system; formal methods in software engineering and safety-critical industries; knowledge representation and ontology engineering; linguistics, where grammars or semantics are encoded; and contract analysis or requirements engineering, where conditions are specified for tooling and checks.

The formalisation process typically includes identifying the informal intent, selecting a suitable formal language and semantics, encoding the concepts into the language, and validating that the formal model preserves the intended behavior. Verification may involve type checking, theorem proving, model checking, or automatic reasoning. Refinement links the formal model to implementation.

Tools and approaches used by formalisers include theorem provers and proof assistants such as Coq and Isabelle/HOL; model checkers and specification languages like Z, VDM, TLA+, and Alloy; and modeling standards such as UML/OCL. The role may be performed by a human analyst, a software tool, or an integrated workflow.

Key challenges include ambiguity in the original specification, trade-offs between expressiveness and tractability, scalability to large systems, and the learning curve for formal methods. Maintaining formal artefacts alongside evolving requirements also poses a practical hurdle.

See also: formal methods, formal specification, formal logic, proof assistant, model checking, verification.