Theorem ss0b 3454

Description: Any subset of the empty set is empty. Theorem 5 of [Suppes] p. 23 and its converse. (Contributed by NM, 17-Sep-2003.)

Assertion

Ref	Expression
ss0b	|- ( A C_ (/) <-> A = (/) )

Proof of Theorem ss0b

Step	Hyp	Ref	Expression
1		0ss 3453	. . 3 |- (/) C_ A
2		eqss 3162	. . 3 |- ( A = (/) <-> ( A C_ (/) /\ (/) C_ A ) )
3	1, 2	mpbiran2 936	. 2 |- ( A = (/) <-> A C_ (/) )
4	3	bicomi 131	1 |- ( A C_ (/) <-> A = (/) )

Syntax hints:   <-> wb 104   = wceq 1348   C_ wss 3121   (/)c0 3414

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 105  ax-ia2 106  ax-ia3 107  ax-in1 609  ax-in2 610  ax-io 704  ax-5 1440  ax-7 1441  ax-gen 1442  ax-ie1 1486  ax-ie2 1487  ax-8 1497  ax-10 1498  ax-11 1499  ax-i12 1500  ax-bndl 1502  ax-4 1503  ax-17 1519  ax-i9 1523  ax-ial 1527  ax-i5r 1528  ax-ext 2152

This theorem depends on definitions:  df-bi 116  df-tru 1351  df-nf 1454  df-sb 1756  df-clab 2157  df-cleq 2163  df-clel 2166  df-nfc 2301  df-v 2732  df-dif 3123  df-in 3127  df-ss 3134  df-nul 3415

This theorem is referenced by:  ss0  3455  un00  3461  ssdisj  3471  pw0  3727  card0  7165  0nnei  12947