,
Santiago Figueira
,
Yoshiki Nakamura
Creative Commons Attribution 4.0 International license
We study the guarded negation fragment of transitive closure logic (GNTC). We show that the satisfiability problem for GNTC is 2ExpTime-complete, by establishing the following reductions: (i) a polynomial-time reduction from the satisfiability problem for GNTC to the satisfiability problem for the unary negation fragment UNTC of GNTC, and (ii) a direct exponential-time reduction from the satisfiability problem for UNTC to the non-emptiness problem for 2-way alternating parity tree automata. Furthermore, we show that the model checking problem for GNTC is 𝖯^NP[𝒪(log² n)]-complete in combined complexity. Our result implies 𝖯^NP[𝒪(log² n)]-completeness for both UNTC and UNFO^reg, which were left open in previous works.
@InProceedings{figueira_et_al:LIPIcs.LICS.2026.43,
author = {Figueira, Diego and Figueira, Santiago and Nakamura, Yoshiki},
title = {{Guarded Negation Transitive Closure Logic}},
booktitle = {41st Annual Symposium on Logic in Computer Science (LICS 2026)},
pages = {43:1--43:29},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-434-5},
ISSN = {1868-8969},
year = {2026},
volume = {380},
editor = {Faggian, Claudia and Katoen, Joost-Pieter},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.LICS.2026.43},
URN = {urn:nbn:de:0030-drops-268302},
doi = {10.4230/LIPIcs.LICS.2026.43},
annote = {Keywords: Transitive closure logic, Guarded negation, Unary negation, Satisfiability, Model checking}
}