Theorem paddunssN

Description: Projective subspace sum includes the set union of its arguments. (Contributed by NM, 12-Jan-2012) (New usage is discouraged.)

	Ref	Expression
Hypotheses	padd0.a	⊢ 𝐴 = ( Atoms ‘ 𝐾 )
	padd0.p	⊢ + = ( +𝑃 ‘ 𝐾 )
Assertion	paddunssN	⊢ ( ( 𝐾 ∈ 𝐵 ∧ 𝑋 ⊆ 𝐴 ∧ 𝑌 ⊆ 𝐴 ) → ( 𝑋 ∪ 𝑌 ) ⊆ ( 𝑋 + 𝑌 ) )

Proof

Step	Hyp	Ref	Expression
1		padd0.a	⊢ 𝐴 = ( Atoms ‘ 𝐾 )
2		padd0.p	⊢ + = ( +𝑃 ‘ 𝐾 )
3		ssun1	⊢ ( 𝑋 ∪ 𝑌 ) ⊆ ( ( 𝑋 ∪ 𝑌 ) ∪ { 𝑝 ∈ 𝐴 ∣ ∃ 𝑞 ∈ 𝑋 ∃ 𝑟 ∈ 𝑌 𝑝 ( le ‘ 𝐾 ) ( 𝑞 ( join ‘ 𝐾 ) 𝑟 ) } )
4		eqid	⊢ ( le ‘ 𝐾 ) = ( le ‘ 𝐾 )
5		eqid	⊢ ( join ‘ 𝐾 ) = ( join ‘ 𝐾 )
6	4 5 1 2	paddval	⊢ ( ( 𝐾 ∈ 𝐵 ∧ 𝑋 ⊆ 𝐴 ∧ 𝑌 ⊆ 𝐴 ) → ( 𝑋 + 𝑌 ) = ( ( 𝑋 ∪ 𝑌 ) ∪ { 𝑝 ∈ 𝐴 ∣ ∃ 𝑞 ∈ 𝑋 ∃ 𝑟 ∈ 𝑌 𝑝 ( le ‘ 𝐾 ) ( 𝑞 ( join ‘ 𝐾 ) 𝑟 ) } ) )
7	3 6	sseqtrrid	⊢ ( ( 𝐾 ∈ 𝐵 ∧ 𝑋 ⊆ 𝐴 ∧ 𝑌 ⊆ 𝐴 ) → ( 𝑋 ∪ 𝑌 ) ⊆ ( 𝑋 + 𝑌 ) )