I'm trying to procedurally generate replacement rules of the following form X[{a,a}] -> X1 X[{a,b}]X[{b,a}] -> X2 X[{a,b}]X[{b,c}]X[{c,a}] -> X3 X[{a,b}]X[{b,c}]X[{c,d}]X[{d,a}] -> X4 Also, I know the number of maximum required replacement rules in advance. ---------- Implementing {a1___, a2___, a3___, ... } instead of {a,b,c, ... }, my pseudocode reads off Xn = X[{a[1],a[2]}] X[{a[2],a[3]}]... X[{a[n-1],a[n]}] X[{a[n],a[1]}] Xn = Product[ X[{a[i],a[i+1]}], {i,1,n-1} ] X[{a[n],a[1]}] which, translated into actual *Mathematica* code, gives me: MyRule[n_] := a___ Product[ Subscript[X, {Symbol["μ"<>ToString[i]<>"___"], Symbol["μ"<>ToString[i+1]<>"___"]}], {i,1,n-1}] Subscript[X, {Symbol["μ"<>ToString[n]<>"___"], Symbol["μ"<>ToString[1]<>"__"]} ] :> a Subscript[X, n] ---------- However, Subscript[X, {a, b}] Subscript[X, {b, a}] /. MyRule[2] shows that the rule definition is not working properly, allegedly, because of a conflict in the way the dummy indices are written and some issues with their 'Symbol' character but I don't really get it.