Peak–end rule end. The effects of the duration of an experience upon retrospective evaluation are extremely slight. Fredrickson and Kahneman labeled this phenomenon "duration neglect". The peak–end rule is applicable only when an experience has definite beginning and end periods. A 1993 study titled "When More Pain Is Preferred to Less: Adding a Better End" by Kahneman, Fredrickson, Charles Schreiber, and Donald Redelmeier provided groundbreaking evidence for the peak–end rule. Participants were subjected to two different versions of a single unpleasant experience. The first trial had subjects submerge a hand in 14 °C water for 60 seconds. The second trial had subjects
General Leibniz rule General Leibniz rule In calculus, the general Leibniz rule, named after Gottfried Wilhelm Leibniz, generalizes the product rule (which is also known as "Leibniz's rule"). It states that if formula_1 and formula_2 are formula_3-times differentiable functions, then the product formula_4 is also formula_3-times differentiable and its formula_3th derivative is given by where formula_8 is the binomial coefficient and formula_9 This can be proved by using the product rule and mathematical induction. If, for example, , the rule gives an expression for the second derivative of a product of two functions: The formula can be generalized to the product of "m"