Space-Efficient Model-Checking of Higher-Order Recursion Schemes

Florian Bruse

Abstract: Model checking trees generated by Higher-Order Recursion Schemes (HORS) of order k against Alternating Parity Tree-Automata (APT) is known to be a k-EXPTIME-complete problem (Ong’06). We exhibit a natural fragment of HORS, called tail-recursive HORS, and a restricted APT model, called bounded-alternation APT, such that the problem of model checking trees generated by order-k tail-recursive HORS against bounded-alternation APT is \(k{-}1\)-EXPSPACE-complete. The upper bound is achieved by converting the problem into an alternating reachability game, the lower one via reduction from a tiling problem.