Abstract
We exhibit a simple inference rule, which is admissible but not derivable in BCK, proving that BCK is not structurally complete. The argument is proof-theoretical.
Citation
Tomasz Kowalski. "BCK is not Structurally Complete." Notre Dame J. Formal Logic 55 (2) 197 - 204, 2014. https://doi.org/10.1215/00294527-2420642
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