CP: a set of codepointsGLP: a subset ofCP+(non-empty sequences)
With the property:
(1) if x in GLP then x+y not in GLP
(for all x,y in CP+)
STR: smallest subset of CP* such that
- empty in
STR - if
sinSTRandxinGLPthenx+sinSTR
Theorem: If s in STR then there exist unique n, and x1, ..., xn in GLP such that s = x1 + ... + xn. We call n the length of s.
If s1 + x1 + ... + xn + s2 in STR and |y1 + ... + ym| = |x1 + ... + xn| then s1 + y1 + ... + ym + s2 in STR.
(for s1, s2 in S and x1, ..., xn and y1, ..., ym in GLP).