Theorem s4cli

Description: A length 4 string is a word. (Contributed by Mario Carneiro, 26-Feb-2016)

	Ref	Expression
Assertion	s4cli	⊢ ⟨“ 𝐴 𝐵 𝐶 𝐷 ”⟩ ∈ Word V

Proof

Step	Hyp	Ref	Expression
1		df-s4	⊢ ⟨“ 𝐴 𝐵 𝐶 𝐷 ”⟩ = ( ⟨“ 𝐴 𝐵 𝐶 ”⟩ ++ ⟨“ 𝐷 ”⟩ )
2		s3cli	⊢ ⟨“ 𝐴 𝐵 𝐶 ”⟩ ∈ Word V
3	1 2	cats1cli	⊢ ⟨“ 𝐴 𝐵 𝐶 𝐷 ”⟩ ∈ Word V