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Database
SUPPLEMENTARY MATERIAL (USERS' MATHBOXES)
Mathbox for Jonathan Ben-Naim
Well founded induction and recursion
bnj958
Metamath Proof Explorer
Description: Technical lemma for bnj69 . This lemma may no longer be used or have
become an indirect lemma of the theorem in question (i.e. a lemma of a
lemma... of the theorem). (Contributed by Jonathan Ben-Naim , 3-Jun-2011) (New usage is discouraged.)
Ref
Expression
Hypotheses
bnj958.1
⊢ C = ⋃ y ∈ f ⁡ m pred y A R
bnj958.2
⊢ G = f ∪ n C
Assertion
bnj958
⊢ G ⁡ i = f ⁡ i → ∀ y G ⁡ i = f ⁡ i
Proof
Step
Hyp
Ref
Expression
1
bnj958.1
⊢ C = ⋃ y ∈ f ⁡ m pred y A R
2
bnj958.2
⊢ G = f ∪ n C
3
nfcv
⊢ Ⅎ _ y f
4
nfcv
⊢ Ⅎ _ y n
5
nfiu1
⊢ Ⅎ _ y ⋃ y ∈ f ⁡ m pred y A R
6
1 5
nfcxfr
⊢ Ⅎ _ y C
7
4 6
nfop
⊢ Ⅎ _ y n C
8
7
nfsn
⊢ Ⅎ _ y n C
9
3 8
nfun
⊢ Ⅎ _ y f ∪ n C
10
2 9
nfcxfr
⊢ Ⅎ _ y G
11
nfcv
⊢ Ⅎ _ y i
12
10 11
nffv
⊢ Ⅎ _ y G ⁡ i
13
12
nfeq1
⊢ Ⅎ y G ⁡ i = f ⁡ i
14
13
nf5ri
⊢ G ⁡ i = f ⁡ i → ∀ y G ⁡ i = f ⁡ i