eprintid: 10199855 rev_number: 10 eprint_status: archive userid: 699 dir: disk0/10/19/98/55 datestamp: 2024-11-11 12:25:49 lastmod: 2024-11-11 12:30:04 status_changed: 2024-11-11 12:25:49 type: article metadata_visibility: show sword_depositor: 699 creators_name: Kürbis, Nils title: Normalisation for negative free logics without and with definite descriptions ispublished: inpress divisions: UCL divisions: B03 divisions: C01 divisions: F16 keywords: Negative free logic; definite descriptions; proof theory; normalisation note: Copyright © The Author(s), 2024. Published by Cambridge University Press on behalf of The Association for Symbolic Logic. This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted re-use, distribution, and reproduction in any medium, provided the original work is properly cited. abstract: This paper proves normalisation theorems for intuitionist and classical negative free logic, without and with the operator for definite descriptions. Rules specific to free logic give rise to new kinds of maximal formulas additional to those familiar from standard intuitionist and classical logic. When is added it must be ensured that reduction procedures involving replacements of parameters by terms do not introduce new maximal formulas of higher degree than the ones removed. The problem is solved by a rule that permits restricting these terms in the rules for ∀ , ∃ and to parameters or constants. A restricted subformula property for deductions in systems without is considered. It is improved upon by an alternative formalisation of free logic building on an idea of Jaśkowski’s. In the classical system the rules for require treatment known from normalisation for classical logic with ∨ or ∃ . The philosophical significance of the results is also indicated. date: 2024-09-03 date_type: published publisher: CAMBRIDGE UNIV PRESS official_url: http://dx.doi.org/10.1017/s1755020324000157 oa_status: green full_text_type: pub language: eng primo: open primo_central: open_green verified: verified_manual elements_id: 2312256 doi: 10.1017/S1755020324000157 lyricists_name: Kurbis, Nils lyricists_id: NKURB54 actors_name: Kurbis, Nils actors_id: NKURB54 actors_role: owner funding_acknowledgements: 101054714 [European Union (ERC, ExtenDD)] full_text_status: public publication: The Review of Symbolic Logic pagerange: 1-33 pages: 33 issn: 1755-0203 citation: Kürbis, Nils; (2024) Normalisation for negative free logics without and with definite descriptions. The Review of Symbolic Logic pp. 1-33. 10.1017/S1755020324000157 <https://doi.org/10.1017/S1755020324000157>. (In press). Green open access document_url: https://discovery.ucl.ac.uk/id/eprint/10199855/1/Kurbis_normalisation-for-negative-free-logics-without-and-with-definite-descriptions.pdf