Theorem s5len

Description: The length of a length 5 string. (Contributed by Mario Carneiro, 26-Feb-2016)

	Ref	Expression
Assertion	s5len	$$⊢\left|⟨“ABCDE”⟩\right|=5$$

Proof

Step	Hyp	Ref	Expression
1		df-s5	$$⊢⟨“ABCDE”⟩=⟨“ABCD”⟩\mathrm{++}⟨“E”⟩$$
2		s4cli	$$⊢⟨“ABCD”⟩\in \mathrm{Word}\mathrm{V}$$
3		s4len	$$⊢\left|⟨“ABCD”⟩\right|=4$$
4		4p1e5	$$⊢4+1=5$$
5	1 2 3 4	cats1len	$$⊢\left|⟨“ABCDE”⟩\right|=5$$