Proof Compression and NP Versus PSPACE II: Addendum


  • Lew Gordeev University of Tübingen, Department of Computer Science, Nedlitzer Str. 4a, 14612 Falkensee image/svg+xml
  • E. Hermann Haeusler Pontificia Universidade Católica do Rio de Janeiro – RJ, Department of Informatics, Rua Marques de São Vicente, 224, Gávea, Rio de Janeiro, Brazil image/svg+xml



graph theory, natural deduction, computational complexity


In our previous work we proved the conjecture NP = PSPACE by advanced proof theoretic methods that combined Hudelmaier’s cut-free sequent calculus for minimal logic (HSC) with the horizontal compressing in the corresponding minimal Prawitz-style natural deduction (ND). In this Addendum we show how to prove a weaker result NP = coNP without referring to HSC. The underlying idea (due to the second author) is to omit full minimal logic and compress only “naive” normal tree-like ND refutations of the existence of Hamiltonian cycles in given non-Hamiltonian graphs, since the Hamiltonian graph problem in NPcomplete. Thus, loosely speaking, the proof of NP = coNP can be obtained by HSC-elimination from our proof of NP = PSPACE.


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How to Cite

Gordeev, L., & Haeusler, E. H. (2022). Proof Compression and NP Versus PSPACE II: Addendum. Bulletin of the Section of Logic, 51(2), 197–205.



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