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27 | 27 | The ``if'' part is |
28 | 28 | \olref[int]{defn:representable-fn}\olref[int]{defn:rep:a}. The ``only |
29 | 29 | if'' part is seen as follows: Suppose $\Th{Q} \Proves !A_f(\num{n_0}, |
30 | | -\dots, \num{n_k}, \num{m})$ but $m \neq f(n_0, \dots, n_k)$. Let $k = |
| 30 | +\dots, \num{n_k}, \num{m})$ but $m \neq f(n_0, \dots, n_k)$. Let $l = |
31 | 31 | f(n_0, \dots, n_k)$. By |
32 | 32 | \olref[int]{defn:representable-fn}\olref[int]{defn:rep:a}, $\Th{Q} |
33 | | -\Proves !A_f(\num{n_0}, \dots, \num{n_k}, \num{k})$. By |
| 33 | +\Proves !A_f(\num{n_0}, \dots, \num{n_k}, \num{l})$. By |
34 | 34 | \olref[int]{defn:representable-fn}\olref[int]{defn:rep:b}, |
35 | | -$\lforall[y][(!A_f(\num{n_0}, \dots, \num{n_k}, y) \lif \num{k} = |
| 35 | +$\lforall[y][(!A_f(\num{n_0}, \dots, \num{n_k}, y) \lif \num{l} = |
36 | 36 | y)]$. Using logic and the assumption that $\Th{Q} \Proves |
37 | 37 | !A_f(\num{n_0}, \dots, \num{n_k}, \num{m})$, we get that $\Th{Q} |
38 | | -\Proves \eq[\num{k}][\num{m}]$. On the other hand, by |
| 38 | +\Proves \eq[\num{l}][\num{m}]$. On the other hand, by |
39 | 39 | \olref[bre]{lem:q-proves-neq}, $\Th{Q} \Proves |
40 | | -\eq/[\num{k}][\num{m}]$. So $\Th{Q}$ is inconsistent. But that is |
| 40 | +\eq/[\num{l}][\num{m}]$. So $\Th{Q}$ is inconsistent. But that is |
41 | 41 | impossible, since $\Th{Q}$ is satisfied by the standard model (see |
42 | 42 | \olref[int][def]{def:standard-model}), $\Sat{N}{\Th{Q}}$, and |
43 | 43 | satisfiable theories are always consistent by the Soundness Theorem |
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