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1 (* Title: Option.ML |
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2 ID: $Id$ |
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3 Author: Tobias Nipkow |
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4 Copyright 1994 TU Muenchen |
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5 |
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6 Derived rules |
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7 *) |
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8 |
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9 Addsimps [Let_def]; |
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10 |
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11 val [prem] = goal Option.thy "P(opt) ==> P(None) | (? x. P(Some(x)))"; |
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12 br (prem RS rev_mp) 1; |
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13 by (Option.option.induct_tac "opt" 1); |
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14 by (ALLGOALS(Fast_tac)); |
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15 val optE = store_thm("optE", standard(result() RS disjE)); |
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16 |
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17 goal Option.thy "x=None | (? y.x=Some(y))"; |
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18 by (Option.option.induct_tac "x" 1); |
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19 by (Asm_full_simp_tac 1); |
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20 by (rtac disjI2 1); |
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21 by (rtac exI 1); |
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22 by (Asm_full_simp_tac 1); |
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23 qed"opt_cases"; |
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