 This rule can be formulated much the same way as my earlier example of a causal statement; 'if you perform action X to subject Y, then Z happens' (Note the cause and effect formulation).This type of algorithmic formulation is called a design solution (vanAken and Romme 2005).A design solution is usually a statistically proven quantitative model that can be taken as specific instruction (van Aken & Romme, 2005).