We present some results regarding languages that are context-free or regular w.r.t. a non-deterministic binary operation on words that is left variable, only asking a few general properties like associativity. This could be part of a unified approach to intertextuality, the results referring, in particular, to important instances of ”putting texts together” operations like concatenation and shu...

the minimal prime decomposition for semiprime ideals is defined and studied on z-ideals of c(x). the necessary and sufficient condition for existence of the minimal prime decomposition of a z-ideal / is given, when / satisfies one of the following conditions: (i) / is an intersection of maximal ideals. (ii) i is an intersection of o , s, when x is basically disconnected. (iii) i=o , when x x ha...