Description: Closure of concatenation with a singleton word. (Contributed by Mario Carneiro, 26-Feb-2016)
Ref | Expression | ||
---|---|---|---|
Hypotheses | cats1cld.1 | ||
cats1cld.2 | |||
cats1cld.3 | |||
Assertion | cats1cld |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | cats1cld.1 | ||
2 | cats1cld.2 | ||
3 | cats1cld.3 | ||
4 | 3 | s1cld | |
5 | ccatcl | ||
6 | 2 4 5 | syl2anc | |
7 | 1 6 | eqeltrid |