Ergodic Theorems and Converses for PSPACE Functions

Autor: Nandakumar, Satyadev, Pulari, Subin
Rok vydání: 2022
Předmět:
Zdroj: Theory of Computing Systems.
ISSN: 1433-0490
1432-4350
DOI: 10.1007/s00224-022-10094-9
Popis: We initiate the study of effective pointwise ergodic theorems in resource-bounded settings. Classically, the convergence of the ergodic averages for integrable functions can be arbitrarily slow [Ulrich Krengel, 1978]. In contrast, we show that for a class of PSPACE L¹ functions, and a class of PSPACE computable measure-preserving ergodic transformations, the ergodic average exists and is equal to the space average on every EXP random. We establish a partial converse that PSPACE non-randomness can be characterized as non-convergence of ergodic averages. Further, we prove that there is a class of resource-bounded randoms, viz. SUBEXP-space randoms, on which the corresponding ergodic theorem has an exact converse - a point x is SUBEXP-space random if and only if the corresponding effective ergodic theorem holds for x.
LIPIcs, Vol. 202, 46th International Symposium on Mathematical Foundations of Computer Science (MFCS 2021), pages 80:1-80:19
Databáze: OpenAIRE