Metamath Proof Explorer


Theorem cstucnd

Description: A constant function is uniformly continuous. Deduction form. Example 1 of BourbakiTop1 p. II.6. (Contributed by Thierry Arnoux, 16-Nov-2017)

Ref Expression
Hypotheses cstucnd.1 ( 𝜑𝑈 ∈ ( UnifOn ‘ 𝑋 ) )
cstucnd.2 ( 𝜑𝑉 ∈ ( UnifOn ‘ 𝑌 ) )
cstucnd.3 ( 𝜑𝐴𝑌 )
Assertion cstucnd ( 𝜑 → ( 𝑋 × { 𝐴 } ) ∈ ( 𝑈 Cnu 𝑉 ) )

Proof

Step Hyp Ref Expression
1 cstucnd.1 ( 𝜑𝑈 ∈ ( UnifOn ‘ 𝑋 ) )
2 cstucnd.2 ( 𝜑𝑉 ∈ ( UnifOn ‘ 𝑌 ) )
3 cstucnd.3 ( 𝜑𝐴𝑌 )
4 fconst6g ( 𝐴𝑌 → ( 𝑋 × { 𝐴 } ) : 𝑋𝑌 )
5 3 4 syl ( 𝜑 → ( 𝑋 × { 𝐴 } ) : 𝑋𝑌 )
6 1 adantr ( ( 𝜑𝑠𝑉 ) → 𝑈 ∈ ( UnifOn ‘ 𝑋 ) )
7 ustne0 ( 𝑈 ∈ ( UnifOn ‘ 𝑋 ) → 𝑈 ≠ ∅ )
8 6 7 syl ( ( 𝜑𝑠𝑉 ) → 𝑈 ≠ ∅ )
9 2 ad3antrrr ( ( ( ( 𝜑𝑠𝑉 ) ∧ 𝑟𝑈 ) ∧ ( 𝑥𝑋𝑦𝑋 ) ) → 𝑉 ∈ ( UnifOn ‘ 𝑌 ) )
10 simpllr ( ( ( ( 𝜑𝑠𝑉 ) ∧ 𝑟𝑈 ) ∧ ( 𝑥𝑋𝑦𝑋 ) ) → 𝑠𝑉 )
11 3 ad3antrrr ( ( ( ( 𝜑𝑠𝑉 ) ∧ 𝑟𝑈 ) ∧ ( 𝑥𝑋𝑦𝑋 ) ) → 𝐴𝑌 )
12 ustref ( ( 𝑉 ∈ ( UnifOn ‘ 𝑌 ) ∧ 𝑠𝑉𝐴𝑌 ) → 𝐴 𝑠 𝐴 )
13 9 10 11 12 syl3anc ( ( ( ( 𝜑𝑠𝑉 ) ∧ 𝑟𝑈 ) ∧ ( 𝑥𝑋𝑦𝑋 ) ) → 𝐴 𝑠 𝐴 )
14 simprl ( ( ( ( 𝜑𝑠𝑉 ) ∧ 𝑟𝑈 ) ∧ ( 𝑥𝑋𝑦𝑋 ) ) → 𝑥𝑋 )
15 fvconst2g ( ( 𝐴𝑌𝑥𝑋 ) → ( ( 𝑋 × { 𝐴 } ) ‘ 𝑥 ) = 𝐴 )
16 11 14 15 syl2anc ( ( ( ( 𝜑𝑠𝑉 ) ∧ 𝑟𝑈 ) ∧ ( 𝑥𝑋𝑦𝑋 ) ) → ( ( 𝑋 × { 𝐴 } ) ‘ 𝑥 ) = 𝐴 )
17 simprr ( ( ( ( 𝜑𝑠𝑉 ) ∧ 𝑟𝑈 ) ∧ ( 𝑥𝑋𝑦𝑋 ) ) → 𝑦𝑋 )
18 fvconst2g ( ( 𝐴𝑌𝑦𝑋 ) → ( ( 𝑋 × { 𝐴 } ) ‘ 𝑦 ) = 𝐴 )
19 11 17 18 syl2anc ( ( ( ( 𝜑𝑠𝑉 ) ∧ 𝑟𝑈 ) ∧ ( 𝑥𝑋𝑦𝑋 ) ) → ( ( 𝑋 × { 𝐴 } ) ‘ 𝑦 ) = 𝐴 )
20 13 16 19 3brtr4d ( ( ( ( 𝜑𝑠𝑉 ) ∧ 𝑟𝑈 ) ∧ ( 𝑥𝑋𝑦𝑋 ) ) → ( ( 𝑋 × { 𝐴 } ) ‘ 𝑥 ) 𝑠 ( ( 𝑋 × { 𝐴 } ) ‘ 𝑦 ) )
21 20 a1d ( ( ( ( 𝜑𝑠𝑉 ) ∧ 𝑟𝑈 ) ∧ ( 𝑥𝑋𝑦𝑋 ) ) → ( 𝑥 𝑟 𝑦 → ( ( 𝑋 × { 𝐴 } ) ‘ 𝑥 ) 𝑠 ( ( 𝑋 × { 𝐴 } ) ‘ 𝑦 ) ) )
22 21 ralrimivva ( ( ( 𝜑𝑠𝑉 ) ∧ 𝑟𝑈 ) → ∀ 𝑥𝑋𝑦𝑋 ( 𝑥 𝑟 𝑦 → ( ( 𝑋 × { 𝐴 } ) ‘ 𝑥 ) 𝑠 ( ( 𝑋 × { 𝐴 } ) ‘ 𝑦 ) ) )
23 22 reximdva0 ( ( ( 𝜑𝑠𝑉 ) ∧ 𝑈 ≠ ∅ ) → ∃ 𝑟𝑈𝑥𝑋𝑦𝑋 ( 𝑥 𝑟 𝑦 → ( ( 𝑋 × { 𝐴 } ) ‘ 𝑥 ) 𝑠 ( ( 𝑋 × { 𝐴 } ) ‘ 𝑦 ) ) )
24 8 23 mpdan ( ( 𝜑𝑠𝑉 ) → ∃ 𝑟𝑈𝑥𝑋𝑦𝑋 ( 𝑥 𝑟 𝑦 → ( ( 𝑋 × { 𝐴 } ) ‘ 𝑥 ) 𝑠 ( ( 𝑋 × { 𝐴 } ) ‘ 𝑦 ) ) )
25 24 ralrimiva ( 𝜑 → ∀ 𝑠𝑉𝑟𝑈𝑥𝑋𝑦𝑋 ( 𝑥 𝑟 𝑦 → ( ( 𝑋 × { 𝐴 } ) ‘ 𝑥 ) 𝑠 ( ( 𝑋 × { 𝐴 } ) ‘ 𝑦 ) ) )
26 isucn ( ( 𝑈 ∈ ( UnifOn ‘ 𝑋 ) ∧ 𝑉 ∈ ( UnifOn ‘ 𝑌 ) ) → ( ( 𝑋 × { 𝐴 } ) ∈ ( 𝑈 Cnu 𝑉 ) ↔ ( ( 𝑋 × { 𝐴 } ) : 𝑋𝑌 ∧ ∀ 𝑠𝑉𝑟𝑈𝑥𝑋𝑦𝑋 ( 𝑥 𝑟 𝑦 → ( ( 𝑋 × { 𝐴 } ) ‘ 𝑥 ) 𝑠 ( ( 𝑋 × { 𝐴 } ) ‘ 𝑦 ) ) ) ) )
27 1 2 26 syl2anc ( 𝜑 → ( ( 𝑋 × { 𝐴 } ) ∈ ( 𝑈 Cnu 𝑉 ) ↔ ( ( 𝑋 × { 𝐴 } ) : 𝑋𝑌 ∧ ∀ 𝑠𝑉𝑟𝑈𝑥𝑋𝑦𝑋 ( 𝑥 𝑟 𝑦 → ( ( 𝑋 × { 𝐴 } ) ‘ 𝑥 ) 𝑠 ( ( 𝑋 × { 𝐴 } ) ‘ 𝑦 ) ) ) ) )
28 5 25 27 mpbir2and ( 𝜑 → ( 𝑋 × { 𝐴 } ) ∈ ( 𝑈 Cnu 𝑉 ) )