Let's say you have a direct sum of n copies of Z12, i.e., Z12_1 + Z12_2... + Z12_n, whose elements are n-tuples of the form: Y_1=(y_1,y_2,...y_n) Note '_' means subscript. Is there a special name/notation for a set/ cycle of twelve n-tuples generated by evaluating: Y_q+1=([y_1]+q, y_2,...y_n), where q ranges from 0 to 12, & '+' is now addition mod12 ; in other words, one entry in the n-tuple varys through all possible values while the others stay constant. Please forgive any awkward notation...I'm a musician working on mathematizing a model I've been developing in pitch class theory. Thanks a bundle...or should I say fibre bundle?---Robby Roiter P.S. Are there any decent basic discrete math educational free resources on the net or do I have to get a book?