Incorrect comments on Logical Pinpointing - Less Wrong

62 Post author: Eliezer_Yudkowsky 02 November 2012 03:33PM

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Comment author: Incorrect 04 November 2012 01:17:30AM 2 points [-]

An infinite number of axioms like in an axiom schema doesn't really hurt anything, but you can't have infinitely long single axioms.

∀x((x = 0) ∨ (x = S0) ∨ (x = SS0) ∨ (x = SSS0) ∨ ...)

is not an option. And neither is the axiom set

P0(x) iff x = 0
PS0(x) iff x = S0
PSS0(x) iff x = SS0
...
∀x(P0(x) ∨ PS0(x) ∨ PS0(x) ∨ PS0(x) ∨ ...)

We could instead try the axioms

P(0, x) iff x = 0
P(S0, x) iff x = S0
P(SS0, x) iff x = SS0
...
∀x(∃n(P(n, x)))

but then again we have the problem of n being a nonstandard number.