We introduce a new framework for a descriptive complexity approach to arithmetic computations. We define a hierarchy of classes based on the idea of counting assignments to free function variables in first-order formulae. We completely determine the inclusion structure and show that #P and #AC^0 appear as classes of this hierarchy. In this way, we unconditionally place #AC^0 properly in a strict hierarchy of arithmetic classes within #P. We compare our classes with a hierarchy within #P defined in a model-theoretic way by Saluja et al. We argue that our approach is better suited to study arithmetic circuit classes such as #AC^0 which can be descriptively characterized as a class in our framework.
@InProceedings{durand_et_al:LIPIcs.CSL.2016.20, author = {Durand, Arnaud and Haak, Anselm and Kontinen, Juha and Vollmer, Heribert}, title = {{Descriptive Complexity of #AC^0 Functions}}, booktitle = {25th EACSL Annual Conference on Computer Science Logic (CSL 2016)}, pages = {20:1--20:16}, series = {Leibniz International Proceedings in Informatics (LIPIcs)}, ISBN = {978-3-95977-022-4}, ISSN = {1868-8969}, year = {2016}, volume = {62}, editor = {Talbot, Jean-Marc and Regnier, Laurent}, publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik}, address = {Dagstuhl, Germany}, URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CSL.2016.20}, URN = {urn:nbn:de:0030-drops-65601}, doi = {10.4230/LIPIcs.CSL.2016.20}, annote = {Keywords: finite model theory, Fagin's theorem, arithmetic circuits, counting classes, Skolem function} }
Feedback for Dagstuhl Publishing