Formal foundations for semi-parsing

There exist many techniques for imprecise manipulation of source code (robust parsing, error repair, lexical analysis, etc), mostly relying on heuristic-based tolerance. Such techniques are rarely fully formalised and quite often idiosyncratic, which makes them very hard to compare with respect to their applicability, tolerance level and general usefulness. With a combination of recently developed formal methods such as Boolean grammars and parsing schemata, we can model different tolerant methods of modelling software and formally argue about relationships between them.