The converse Buridan formula is shown to be invalid

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Tree Proof Generator

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The converse Buridan formula is shown to be invalid #22

Closed MichaelRushton closed 1 year ago

MichaelRushton commented 1 year ago

https://en.wikipedia.org/wiki/Buridan_formula

https://www.umsu.de/trees/#~6x~9Fx~5~9~6xFx (∀x◇Fx→◇∀xFx) https://www.umsu.de/trees/#~8~7xFx~5~7x~8Fx (□∃xFx→∃x□Fx)

wo commented 1 year ago

I don't see why this is an issue. The converse Buridan formula is invalid in standard constant domain semantics, and the prover correctly displays a countermodel.