Dear Colleagues, I am preparing notes for a sophomore (second year) course, and I am finding several places wherein I can find no standard notation. Your suggestions will be most appreciated. (1) Everybody knows that {(n,n+1) | n \in Z} is the <<successor>> relation. What to call the corresponding idea when the underlying order is only a partial order? I am currently using <<followers>> as in phrases such as ``...the followers relation for the subsets of the finite set {a, b, c}...'' in which ({a},{a,b}) is in the followers relation, but {{a},{a,b,c}) is not, anymore that (n,n+2) is in the successor relation. Is there a better word than <<followers>>? (2) I need a snappy name for an order pair in a relation R. The books I have seem to just say ``...the ordered pair (x,y) in relation R...'' The problem is that there are many uses of ordered pairs, and this is a specific use, a description of the fact that x is R-related to y by the fact that (x,y) \in R. The word ``association'' will not do as this has other meaning in computer science. I am considered <<relator>> for an order pair in a relation, but have the impression that this word has been used for other purposes in the literature. (3) I badly need a good name for the sets Nat_k = {n \in Nat | n < k } These are widely used and I am surprised that there is no satisfactory name in wide-spread use. These are NOT the sets Z_k = Z mod k, although the Nat_k form a system of distinct, canonical representatives for the Z_k. These are the set of array indices in computer languages such as C and SML. In this use, the Nat_k have nothing whatsoever to do with Z_k and I certainly do not want to confuse the students! Thank you in advance for any and all suggestions, David -- Professor David B. Benson (509) 335-2706 School of EE and Computer Science (EME 102A) (509) 335-3818 fax PO Box 642752, Washington State University dbenson@eecs.wsu.edu Pullman WA 99164-2752 U.S.A.