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Metamath Proof Explorer

Theorem oi0

Description: Definition of the ordinal isomorphism when its arguments are not meaningful. (Contributed by Mario Carneiro, 25-Jun-2015)

Ref Expression
Hypothesis oicl.1 ⊢ 𝐹 = OrdIso ( 𝑅 , 𝐴 )
Assertion oi0 ( ¬ ( 𝑅 We 𝐴 ∧ 𝑅 Se 𝐴 ) → 𝐹 = ∅ )

Proof

Step Hyp Ref Expression
1 oicl.1 ⊢ 𝐹 = OrdIso ( 𝑅 , 𝐴 )
2 df-oi ⊢ OrdIso ( 𝑅 , 𝐴 ) = if ( ( 𝑅 We 𝐴 ∧ 𝑅 Se 𝐴 ) , ( recs ( ( ℎ ∈ V ↦ ( ℩ 𝑣 ∈ { 𝑤 ∈ 𝐴 ∣ ∀ 𝑗 ∈ ran ℎ 𝑗 𝑅 𝑤 } ∀ 𝑢 ∈ { 𝑤 ∈ 𝐴 ∣ ∀ 𝑗 ∈ ran ℎ 𝑗 𝑅 𝑤 } ¬ 𝑢 𝑅 𝑣 ) ) ) ↾ { 𝑥 ∈ On ∣ ∃ 𝑡 ∈ 𝐴 ∀ 𝑧 ∈ ( recs ( ( ℎ ∈ V ↦ ( ℩ 𝑣 ∈ { 𝑤 ∈ 𝐴 ∣ ∀ 𝑗 ∈ ran ℎ 𝑗 𝑅 𝑤 } ∀ 𝑢 ∈ { 𝑤 ∈ 𝐴 ∣ ∀ 𝑗 ∈ ran ℎ 𝑗 𝑅 𝑤 } ¬ 𝑢 𝑅 𝑣 ) ) ) “ 𝑥 ) 𝑧 𝑅 𝑡 } ) , ∅ )
3 1 2 eqtri ⊢ 𝐹 = if ( ( 𝑅 We 𝐴 ∧ 𝑅 Se 𝐴 ) , ( recs ( ( ℎ ∈ V ↦ ( ℩ 𝑣 ∈ { 𝑤 ∈ 𝐴 ∣ ∀ 𝑗 ∈ ran ℎ 𝑗 𝑅 𝑤 } ∀ 𝑢 ∈ { 𝑤 ∈ 𝐴 ∣ ∀ 𝑗 ∈ ran ℎ 𝑗 𝑅 𝑤 } ¬ 𝑢 𝑅 𝑣 ) ) ) ↾ { 𝑥 ∈ On ∣ ∃ 𝑡 ∈ 𝐴 ∀ 𝑧 ∈ ( recs ( ( ℎ ∈ V ↦ ( ℩ 𝑣 ∈ { 𝑤 ∈ 𝐴 ∣ ∀ 𝑗 ∈ ran ℎ 𝑗 𝑅 𝑤 } ∀ 𝑢 ∈ { 𝑤 ∈ 𝐴 ∣ ∀ 𝑗 ∈ ran ℎ 𝑗 𝑅 𝑤 } ¬ 𝑢 𝑅 𝑣 ) ) ) “ 𝑥 ) 𝑧 𝑅 𝑡 } ) , ∅ )
4 iffalse ⊢ ( ¬ ( 𝑅 We 𝐴 ∧ 𝑅 Se 𝐴 ) → if ( ( 𝑅 We 𝐴 ∧ 𝑅 Se 𝐴 ) , ( recs ( ( ℎ ∈ V ↦ ( ℩ 𝑣 ∈ { 𝑤 ∈ 𝐴 ∣ ∀ 𝑗 ∈ ran ℎ 𝑗 𝑅 𝑤 } ∀ 𝑢 ∈ { 𝑤 ∈ 𝐴 ∣ ∀ 𝑗 ∈ ran ℎ 𝑗 𝑅 𝑤 } ¬ 𝑢 𝑅 𝑣 ) ) ) ↾ { 𝑥 ∈ On ∣ ∃ 𝑡 ∈ 𝐴 ∀ 𝑧 ∈ ( recs ( ( ℎ ∈ V ↦ ( ℩ 𝑣 ∈ { 𝑤 ∈ 𝐴 ∣ ∀ 𝑗 ∈ ran ℎ 𝑗 𝑅 𝑤 } ∀ 𝑢 ∈ { 𝑤 ∈ 𝐴 ∣ ∀ 𝑗 ∈ ran ℎ 𝑗 𝑅 𝑤 } ¬ 𝑢 𝑅 𝑣 ) ) ) “ 𝑥 ) 𝑧 𝑅 𝑡 } ) , ∅ ) = ∅ )
5 3 4 eqtrid ⊢ ( ¬ ( 𝑅 We 𝐴 ∧ 𝑅 Se 𝐴 ) → 𝐹 = ∅ )