Def  is_assoc(A; x,z.f(x;z)) == x,y,z:A. f(x;f(y;z)) = f(f(x;y);z)  A

is mentioned by

Def  is_assoc_sep(A; f) == is_assoc(A; x,y.(f(x,y)))

[is_assoc_sep]

Try larger context: DiscrMathExt IF YOU CAN SEE THIS go to /sfa/Nuprl/Shared/Xindentation_hack_doc.html