If one numeric parameter is a function of another, then the tabulation of the values of the two parameters can be replaced by a tabulation of the values of the independent parameter and the function. For example, data consisting of the pairs "X=1.0, Y=3.0; X=1.2, Y=3.2; X=2.7, Y=4.7; X=5.9, Y=7.9'' can be replaced by the rule "Y = X+2.0" and the values "X=1.0; X=1.2; X=2.7; X=5.9". Of course, one has to be sure that the rule is shorter than the data. Any K points can be interpolated by a K-1 degree polynomial, but since the polynomial requires K coefficients there is no gain in compactness.