Eric and the rest Look - there is nothing particularly mysterious about nested loops and their incorporation into NLP. In Transformational Grammar, certain structures have been the focus of study for decades. Within this set are a special subset called dependencies: in particular, the so-called nested loops are either properly or improperly nested dependencies. The properly nested dependencies are also known as center embedded structures. Take the following sequence: The dog ran away The dog the cat scratched ran away The dog the cat the horse kicked scratched ran away The build up in the sequence of sentences above is an example of a properly nested, center embedded linguistic structure. It is traditionally classified as well-formed and nearly impossible to process perceptually - an example of the competence/performance distinction made in the chapter Intellectual Antecedentes of NLP in Whispering by Carmen and me. This is one of the most frequently borrowed, adapted and utilized structure from linguistics in the context of NLP. In straight linguistics, it is important as it demonstrates that the dependencies involved (subject/verb concordance) in natural language can be separated by a potentially infinite amount of intervening linguistic material. This is one of the classic arguments in linguistic for what are called essential variables in capturing the syntactic structure of a natural language. In NLP, you can find it used extensively in the structure of metaphors: you begin with story 1, midway through it, you make a transition into story 2; midway through it you move into story 3,... through n stories. You then complete the nth story, then the n-1 story,... until story 1 is finally completed. Fluent speakers of German will easily recongize portions of this structure as German sends all verbs (but the initial one) to the end of the sentence (clause) in the reverse order - thereby mirroring the structural properties of this properly nested center embedded form. The psychological effect is to overwhelm the conscious mind processing mechanisms and the client typical enters an altered state which can then be utilized by the agent of change. So, what's the question - your ability to use such structures simply depend on the discipline to practice. On pages 204 - 207 in Whispering, Carmen and I offer a brief description of another application of a related structure. John