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Mirrors > Home > MPE Home > Th. List > dfin3 | Structured version Visualization version Unicode version |
Description: Intersection defined in terms of union (De Morgan's law). Similar to Exercise 4.10(n) of [Mendelson] p. 231. (Contributed by NM, 8-Jan-2002.) |
Ref | Expression |
---|---|
dfin3 |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | ddif 3742 | . 2 | |
2 | dfun2 3859 | . . . 4 | |
3 | ddif 3742 | . . . . . 6 | |
4 | 3 | difeq1i 3724 | . . . . 5 |
5 | 4 | difeq2i 3725 | . . . 4 |
6 | 2, 5 | eqtri 2644 | . . 3 |
7 | 6 | difeq2i 3725 | . 2 |
8 | dfin2 3860 | . 2 | |
9 | 1, 7, 8 | 3eqtr4ri 2655 | 1 |
Colors of variables: wff setvar class |
Syntax hints: wceq 1483 cvv 3200 cdif 3571 cun 3572 cin 3573 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1722 ax-4 1737 ax-5 1839 ax-6 1888 ax-7 1935 ax-9 1999 ax-10 2019 ax-11 2034 ax-12 2047 ax-13 2246 ax-ext 2602 |
This theorem depends on definitions: df-bi 197 df-or 385 df-an 386 df-tru 1486 df-ex 1705 df-nf 1710 df-sb 1881 df-clab 2609 df-cleq 2615 df-clel 2618 df-nfc 2753 df-ral 2917 df-rab 2921 df-v 3202 df-dif 3577 df-un 3579 df-in 3581 |
This theorem is referenced by: difindi 3881 |
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