Abstract
In this paper we show that the Gupta-Belnap systems $\mathbf{S}^{＃}$ and ${\bf S}^*$ are $\Pi^1_2$. Since Kremer has independently established that they are $\Pi^1_2$-hard, this completely settles the problem of their complexity. The above-mentioned upper bound is established through a reduction to countable revision sequences that is inspired by, and makes use of a construction of McGee.
Citation
Gian Aldo Antonelli. "The Complexity of Revision." Notre Dame J. Formal Logic 35 (1) 67 - 72, Winter 1994. https://doi.org/10.1305/ndjfl/1040609294
Information
