Some of the best-known results in mechanism design depend critically on Myerson’s (Math Oper Res 6:58–73, <CitationRef CitationID="CR22">1981</CitationRef>) regularity condition. For example, the second-price auction with reserve price is revenue maximizing only if the type distribution is regular. This paper offers two main findings....</citationref>

When the price of an input factor to a production process increases, then the optimal output level declines and the input is substituted by other factors. Marshall's rule is a formula that determines the own-price elasticity for one factor as a weighted sum of the elasticities of output market...