A computer implemented method of graphically defining a formula comprises the steps of: providing a graphically defined formula including one or more objects that graphically define the formula; selecting one or more of the objects to be grouped into a new component object; determining the number of connections that provide an input to the selected objects; determining the number of connections that provide an output to the selected objects; determining a graphical definition of the formula, where the selected objects are replaced with a representation of the new component object having the determined number of inputs and the determined number of outputs, connection(s) inputting to the selected objects from other objects are replaced with connection(s) connecting to the input(s) of the new component object and connection(s) outputting from the selected objects to the other objects are replaced with connection(s) connecting from the output(s) of the new component object; and determining a logical definition of the formula, where the selected objects are retained in the logical definition.