Metamath Proof Explorer


Theorem infunsdom

Description: The union of two sets that are strictly dominated by the infinite set X is also strictly dominated by X . (Contributed by Mario Carneiro, 3-May-2015)

Ref Expression
Assertion infunsdom ( ( ( 𝑋 ∈ dom card ∧ ω ≼ 𝑋 ) ∧ ( 𝐴𝑋𝐵𝑋 ) ) → ( 𝐴𝐵 ) ≺ 𝑋 )

Proof

Step Hyp Ref Expression
1 sdomdom ( 𝐴𝐵𝐴𝐵 )
2 infunsdom1 ( ( ( 𝑋 ∈ dom card ∧ ω ≼ 𝑋 ) ∧ ( 𝐴𝐵𝐵𝑋 ) ) → ( 𝐴𝐵 ) ≺ 𝑋 )
3 2 anass1rs ( ( ( ( 𝑋 ∈ dom card ∧ ω ≼ 𝑋 ) ∧ 𝐵𝑋 ) ∧ 𝐴𝐵 ) → ( 𝐴𝐵 ) ≺ 𝑋 )
4 3 adantlrl ( ( ( ( 𝑋 ∈ dom card ∧ ω ≼ 𝑋 ) ∧ ( 𝐴𝑋𝐵𝑋 ) ) ∧ 𝐴𝐵 ) → ( 𝐴𝐵 ) ≺ 𝑋 )
5 1 4 sylan2 ( ( ( ( 𝑋 ∈ dom card ∧ ω ≼ 𝑋 ) ∧ ( 𝐴𝑋𝐵𝑋 ) ) ∧ 𝐴𝐵 ) → ( 𝐴𝐵 ) ≺ 𝑋 )
6 simpll ( ( ( 𝑋 ∈ dom card ∧ ω ≼ 𝑋 ) ∧ ( 𝐴𝑋𝐵𝑋 ) ) → 𝑋 ∈ dom card )
7 sdomdom ( 𝐵𝑋𝐵𝑋 )
8 7 ad2antll ( ( ( 𝑋 ∈ dom card ∧ ω ≼ 𝑋 ) ∧ ( 𝐴𝑋𝐵𝑋 ) ) → 𝐵𝑋 )
9 numdom ( ( 𝑋 ∈ dom card ∧ 𝐵𝑋 ) → 𝐵 ∈ dom card )
10 6 8 9 syl2anc ( ( ( 𝑋 ∈ dom card ∧ ω ≼ 𝑋 ) ∧ ( 𝐴𝑋𝐵𝑋 ) ) → 𝐵 ∈ dom card )
11 sdomdom ( 𝐴𝑋𝐴𝑋 )
12 11 ad2antrl ( ( ( 𝑋 ∈ dom card ∧ ω ≼ 𝑋 ) ∧ ( 𝐴𝑋𝐵𝑋 ) ) → 𝐴𝑋 )
13 numdom ( ( 𝑋 ∈ dom card ∧ 𝐴𝑋 ) → 𝐴 ∈ dom card )
14 6 12 13 syl2anc ( ( ( 𝑋 ∈ dom card ∧ ω ≼ 𝑋 ) ∧ ( 𝐴𝑋𝐵𝑋 ) ) → 𝐴 ∈ dom card )
15 domtri2 ( ( 𝐵 ∈ dom card ∧ 𝐴 ∈ dom card ) → ( 𝐵𝐴 ↔ ¬ 𝐴𝐵 ) )
16 10 14 15 syl2anc ( ( ( 𝑋 ∈ dom card ∧ ω ≼ 𝑋 ) ∧ ( 𝐴𝑋𝐵𝑋 ) ) → ( 𝐵𝐴 ↔ ¬ 𝐴𝐵 ) )
17 16 biimpar ( ( ( ( 𝑋 ∈ dom card ∧ ω ≼ 𝑋 ) ∧ ( 𝐴𝑋𝐵𝑋 ) ) ∧ ¬ 𝐴𝐵 ) → 𝐵𝐴 )
18 uncom ( 𝐴𝐵 ) = ( 𝐵𝐴 )
19 infunsdom1 ( ( ( 𝑋 ∈ dom card ∧ ω ≼ 𝑋 ) ∧ ( 𝐵𝐴𝐴𝑋 ) ) → ( 𝐵𝐴 ) ≺ 𝑋 )
20 18 19 eqbrtrid ( ( ( 𝑋 ∈ dom card ∧ ω ≼ 𝑋 ) ∧ ( 𝐵𝐴𝐴𝑋 ) ) → ( 𝐴𝐵 ) ≺ 𝑋 )
21 20 anass1rs ( ( ( ( 𝑋 ∈ dom card ∧ ω ≼ 𝑋 ) ∧ 𝐴𝑋 ) ∧ 𝐵𝐴 ) → ( 𝐴𝐵 ) ≺ 𝑋 )
22 21 adantlrr ( ( ( ( 𝑋 ∈ dom card ∧ ω ≼ 𝑋 ) ∧ ( 𝐴𝑋𝐵𝑋 ) ) ∧ 𝐵𝐴 ) → ( 𝐴𝐵 ) ≺ 𝑋 )
23 17 22 syldan ( ( ( ( 𝑋 ∈ dom card ∧ ω ≼ 𝑋 ) ∧ ( 𝐴𝑋𝐵𝑋 ) ) ∧ ¬ 𝐴𝐵 ) → ( 𝐴𝐵 ) ≺ 𝑋 )
24 5 23 pm2.61dan ( ( ( 𝑋 ∈ dom card ∧ ω ≼ 𝑋 ) ∧ ( 𝐴𝑋𝐵𝑋 ) ) → ( 𝐴𝐵 ) ≺ 𝑋 )