there really ought to be a separate directory called "embeddings"
I'll make one & move stuff over when I have time.

all the kernel stuff should probably be in embeddings

str_ab2fsa
takes a string u1, and two reals a and b
and returns a DFSA M which accepts the reglang
$L=\{u\in\Sigma^* | b+\alpha K(u_1,u) >0\}$
where K is the modular n-gram kernel.