term_expansion(L is R, algebra_isa(L,R)).
algebra_isa(L,R):-grab_vars(L,Lvs),grab_vars(R,Rvs), ...

equation(X,+,Y,Z):- var(X),X is Z-Y.
equation(X,+,Y,Z):- var(Y),Y is Z-X.
equation(X,+,Y,Z):- var(Z),Z is X+Y.
equation(X,-,Y,Z):- var(X),X is Z+Y.
equation(X,-,Y,Z):- var(Y),Y is Z+X.
equation(X,-,Y,Z):- var(Z),Z is X-Y.
equation(X,*,Y,Z):- var(X),X is Z/Y.
equation(X,*,Y,Z):- var(Y),Y is Z/X.
equation(X,*,Y,Z):- var(Z),Z is X*Y.
equation(X,/,Y,Z):- var(X),X is Z*Y.
equation(X,/,Y,Z):- var(Y),Y is Z*X.
equation(X,/,Y,Z):- var(Z),Z is X/Y.