Aliasing has been a problem in both formal verification and practical programming for a number of years. To the formalist, it can be annoyingly difficult to prove the simple Hoare formula {x = true} y := false {x = true}. If x and y refer to the same boolean variable, i.e., x and y are aliased , then the formula will not be valid, and proving that aliasing cannot occur is not always straightforward. To the practicing programmer, aliases can result in mysterious bugs as variables change their values seemingly on their own. A classic example is the matrix multiply routine mult(left, right, result) which puts the product of its first two parameters into the third. This works perfectly well until the day some unsuspecting programmer writes the very reasonable statement mult(a, b, a). If the implementor of the routine did not consider the possibility that an argument may be aliased with the result, disaster is inevitable.

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Abstract. In November 1998 the authors participated in a two-day workshop on the Object Constraint Language (OCL) in Amsterdam. The focus was to clarify issues about the semantics and the use of OCL, and to discuss useful and necessary extensions of OCL. Various topics have been raised and clarified. This manifesto contains the results of that workshop and the following work on these topics. Overview of OCL.

Necrotizing fasciitis is a rapidly progressive, life-threatening soft tissue infection which is rapidly fatal unless diagnosed promptly and treated with immediate debridement of necrotic tissue. As early clinical suspicion is paramount to improved survival, this review aims to increase awareness of the condition.

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