2 ms·
Nope, I'm pretty sure it's not wrong. I believe ϵ is the multiplicative identity ("1") here. Note that ϵ is the empty string, and concatenating it with anything
by dataflow 8y ago
Nope, I'm pretty sure it's not wrong. I believe ϵ is the multiplicative identity ("1") here. Note that ϵ is the empty string, and concatenating it with anything results in the same thing, so Aϵ = A. Hence we have Aϵ - Aa = A(ϵ - a) = ϵ.