THE PHENOMENON OF NON-RECURSIVE TRADE-OFFS
Martin Kutrib · International Journal of Foundations of Computer Science · 2005
Non-recursive trade-offs between different representations of languages reveal a basic phenomenon. The gain in economy of description can be arbitrary. The purpose of this paper is to survey the main aspects and results regarding different representations of languages whose relative succinctness is not recursively bounded. Basic properties of descriptional systems and reasonable size measures are addressed, and the unified fundamental proof schemes emerging from the literature are presented. A comprehensive overview of results is given. Finally, some new results are shown. In particular, it is proved that between each two levels of the infinite one-way k-head finite automata hierarchies there is a non-recursive trade-off. Moreover, non-recursive trade-offs are shown between nondeterministic 2-head and deterministic k-head automata.