Description: Lemma for setrec1 . If a family of sets are all recursively generated by F , so is their union. In this theorem, X is a family of sets which are all elements of Y , and V is any class. Use dfss3 , equivalence and equality theorems, and unissb at the end. Sandwich with applications of setrec1lem1. (Contributed by Emmett Weisz, 24-Jan-2021) (New usage is discouraged.)
Ref | Expression | ||
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Hypotheses | setrec1lem2.1 | |
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setrec1lem2.2 | |
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setrec1lem2.3 | |
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Assertion | setrec1lem2 | |
Step | Hyp | Ref | Expression |
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1 | setrec1lem2.1 | |
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2 | setrec1lem2.2 | |
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3 | setrec1lem2.3 | |
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4 | dfss3 | |
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5 | 3 4 | sylib | |
6 | vex | |
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7 | 6 | a1i | |
8 | 1 7 | setrec1lem1 | |
9 | 8 | ralbidv | |
10 | 5 9 | mpbid | |
11 | ralcom4 | |
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12 | 10 11 | sylib | |
13 | nfra1 | |
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14 | nfv | |
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15 | rsp | |
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16 | elssuni | |
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17 | sstr2 | |
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18 | 16 17 | syl5com | |
19 | 18 | imim1d | |
20 | 19 | alimdv | |
21 | 20 | imim1d | |
22 | 15 21 | sylcom | |
23 | 22 | com23 | |
24 | 13 14 23 | ralrimd | |
25 | 24 | alimi | |
26 | 12 25 | syl | |
27 | unissb | |
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28 | 27 | imbi2i | |
29 | 28 | albii | |
30 | 26 29 | sylibr | |
31 | 2 | uniexd | |
32 | 1 31 | setrec1lem1 | |
33 | 30 32 | mpbird | |