Timeline for Is this well-formed formula for predicate logic?
Current License: CC BY-SA 4.0
10 events
| when toggle format | what | by | license | comment | |
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| Aug 3, 2018 at 23:23 | comment | added | blub | Note, that there is even more to be said about the use of variables as there is an intricate relationship, even in the specification alone of the syntax of first order logic, of the object and meta language. | |
| Aug 3, 2018 at 23:22 | vote | accept | Philip D'Souza | ||
| Aug 3, 2018 at 23:21 | comment | added | blub | Well, under your assumptions that $X,Y$ are predicate symbols, the whole formula becomes rather broken. The main point I wanted to make is that it always depends on the signature and more generally the surroundings on which you built the set of well-formed formulas like the set of variable symbols. Once you've specified these, there is a definite procedure to assert membership. | |
| Aug 3, 2018 at 23:18 | comment | added | Philip D'Souza | So really, only (i) is well-formed depending on the assumptions of the signature. | |
| Aug 3, 2018 at 23:13 | comment | added | blub | I thought so. But taking these assumptions you can now re-verify your findings. | |
| Aug 3, 2018 at 23:12 | comment | added | Philip D'Souza | Wow, comprehensive, thank you. There is no other context given I can assure you. I think it's assumed the lowercase characters are the variables. For (iii) I mistook the U for a disjunction instead of a function. | |
| Aug 3, 2018 at 22:53 | comment | added | blub | @DougSpoonwood You are perfectly right I preached firm grounds and you caught me using an abbreviation. Let me add this in. Thank you. This just comes with the length | |
| Aug 3, 2018 at 22:52 | history | edited | blub | CC BY-SA 4.0 |
added 895 characters in body
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| Aug 3, 2018 at 22:52 | comment | added | Doug Spoonwood | If ∈ is a binary predicate, (i) is not well-formed, since we have x ∈ X instead of the well-formed ∈(x, X). | |
| Aug 3, 2018 at 22:33 | history | answered | blub | CC BY-SA 4.0 |