Theorem nfci 2741

Description: Deduce that a class 𝐴 does not have 𝑥 free in it. (Contributed by Mario Carneiro, 11-Aug-2016.)

Hypothesis

Ref	Expression
nfci.1	⊢ Ⅎ𝑥 𝑦 ∈ 𝐴

Assertion

Ref	Expression
nfci	⊢ Ⅎ𝑥𝐴

Distinct variable groups:   𝑥,𝑦   𝑦,𝐴

Allowed substitution hint:   𝐴(𝑥)

Proof of Theorem nfci

Step	Hyp	Ref	Expression
1		df-nfc 2740	. 2 ⊢ (Ⅎ𝑥𝐴 ↔ ∀𝑦Ⅎ𝑥 𝑦 ∈ 𝐴)
2		nfci.1	. 2 ⊢ Ⅎ𝑥 𝑦 ∈ 𝐴
3	1, 2	mpgbir 1717	1 ⊢ Ⅎ𝑥𝐴

Syntax hints:  Ⅎwnf 1699   ∈ wcel 1977  Ⅎwnfc 2738

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1713

This theorem depends on definitions:  df-bi 196  df-nfc 2740

This theorem is referenced by:  nfcii  2742  nfcv  2751  nfab1  2753  nfab  2755  fpwrelmap  28896  esumfzf  29458  bj-nfab1  31973  fsumiunss  38642  climsuse  38675  climinff  38678  fnlimfvre  38741  pimdecfgtioc  39602  pimincfltioc  39603  smfmullem4  39679