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OpenLogicProject / fitch-checker

JavaScript/PHP Fitch-style natural deduction proof editor and checker (NO LONGER MAINTAINED)
GNU General Public License v3.0
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Are formulas with more than 3 quantifiers intentionally excluded? #14

Open heidelberg1386 opened 3 years ago

heidelberg1386 commented 3 years ago

First of all, thanks for your great project.

Given that all lowercase letters other than x, y and z are interpreted as names, it appears to me that proofs with formals with four quantifiers are impossible to express.

Eg Aw Ax Ay Az (Rwxyz) returns "not well formed".

Is there any way to avoid this? If not: I know this exceeds the scope of a github issue, but do you know of any proof checking software (FOL with Identity) that is easy enough to understand in which I can express these formulas?

Best wishes from Germany, Johannes

rzach commented 3 years ago

I'm not actually maintaining this since I didn't write it. Maybe @frabjous has an answer.

I now use carnap.io for everything since it can automatically grade student work. It does support arbitrary quantifier blocks. See https://carnap.io/shared/rzach@ucalgary.ca/Practice%20Problems%20VII.md (scroll to very end for a box for arbitrary proofs)