,
Mika Göös,
Siyao Guo
,
Gilbert Maystre
,
Weiqiang Yuan
Creative Commons Attribution 4.0 International license
Direct sum theorems state that the cost of solving k instances of a problem is at least Ω(k) times the cost of solving a single instance. We prove the first such results in the randomised parity decision tree model. We show that a direct sum theorem holds whenever (1) the lower bound for parity decision trees is proved using the discrepancy method; or (2) the lower bound is proved relative to a product distribution.
@InProceedings{besselman_et_al:LIPIcs.CCC.2025.16,
author = {Besselman, Tyler and G\"{o}\"{o}s, Mika and Guo, Siyao and Maystre, Gilbert and Yuan, Weiqiang},
title = {{Direct Sums for Parity Decision Trees}},
booktitle = {40th Computational Complexity Conference (CCC 2025)},
pages = {16:1--16:38},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-379-9},
ISSN = {1868-8969},
year = {2025},
volume = {339},
editor = {Srinivasan, Srikanth},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CCC.2025.16},
URN = {urn:nbn:de:0030-drops-237105},
doi = {10.4230/LIPIcs.CCC.2025.16},
annote = {Keywords: direct sum, parity decision trees, query complexity}
}