Metamath Proof Explorer |
< Previous
Next >
Nearby theorems |
||
Mirrors > Home > MPE Home > Th. List > neq0 | Structured version Visualization version GIF version |
Description: A nonempty class has at least one element. Proposition 5.17(1) of [TakeutiZaring] p. 20. (Contributed by NM, 21-Jun-1993.) |
Ref | Expression |
---|---|
neq0 | ⊢ (¬ 𝐴 = ∅ ↔ ∃𝑥 𝑥 ∈ 𝐴) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | nfcv 2764 | . 2 ⊢ Ⅎ𝑥𝐴 | |
2 | 1 | neq0f 3926 | 1 ⊢ (¬ 𝐴 = ∅ ↔ ∃𝑥 𝑥 ∈ 𝐴) |
Colors of variables: wff setvar class |
Syntax hints: ¬ wn 3 ↔ wb 196 = wceq 1483 ∃wex 1704 ∈ wcel 1990 ∅c0 3915 |
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-v 3202 df-dif 3577 df-nul 3916 |
This theorem is referenced by: ralidm 4075 falseral0 4081 snprc 4253 pwpw0 4344 sssn 4358 pwsnALT 4429 uni0b 4463 disjor 4634 isomin 6587 mpt2xneldm 7338 mpt2xopynvov0g 7340 mpt2xopxnop0 7341 erdisj 7794 ixpprc 7929 domunsn 8110 sucdom2 8156 isinf 8173 nfielex 8189 enp1i 8195 xpfi 8231 scottex 8748 acndom 8874 axcclem 9279 axpowndlem3 9421 canthp1lem1 9474 isumltss 14580 pf1rcl 19713 ppttop 20811 ntreq0 20881 txindis 21437 txconn 21492 fmfnfm 21762 ptcmplem2 21857 ptcmplem3 21858 bddmulibl 23605 g0wlk0 26548 wwlksnndef 26800 clwwlksnndef 26890 strlem1 29109 disjorf 29392 ddemeas 30299 tgoldbachgt 30741 bnj1143 30861 poimirlem25 33434 poimirlem27 33436 ineleq 34119 fnchoice 39188 founiiun0 39377 nzerooringczr 42072 |
Copyright terms: Public domain | W3C validator |