SUMMARYWe show that any continuous plane path that turns to the left has a well-deÿned distribution that corresponds to the radius of curvature of smooth paths. We show that the distributional radius of curvature determines the path uniquely except for a translation. We show that Dirac delta contributions in the radius of curvature correspond to facets, that is, at sections of the path, and show how a path can be deformed into a facet by letting the radius of curvature approach a delta function. Copyright
DIVISION BY ZEROEven in the very ÿrst stages of the teaching of mathematics, starting in elementary school, students are taught that one cannot divide by zero. This is important, of course, since division by zero is not well deÿned, and can yield non-sensical results.There are, however, several mathematical frameworks where one can consider the division by zero in a mathematically sound fashion. For instance, when studying indeterminate forms of limits in calculus, one uses the symbolic expression K=0 = ± ∞, which is a shorthand to the fact that if lim x→a f(x) = K = 0, and lim x→a g(x) = 0, with g(x) = 0 for x close to a but di erent from a, then lim x→a f(x)=g(x) = ± ∞, the sign being determined by the sign of K and the sign of g(x) near x = a. Similarly, in the theory of analytic functions it is convenient to consider the range of a meromorphic function to be C = C ∪ {∞}, the Riemann sphere, and deÿne the value of a meromorphic function at a pole to be ∞; thus, if f and g are analytic in a region , a ∈ , and f(a) = K = 0, while g(a) = 0, then the value of h(z) = f(z)=g(z) at z = a is ∞, which in a colourful way can be written as K=0 = ∞.Our aim in the present article is, however, to point out that in several cases the division by 0 could be interpreted not as ∞ but as a suitable Dirac delta function. That this is the * Correspondence to: