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Re: Expressions with ellipsis (...)
On 11/2/08 at 1:58 AM, siegman at stanford.edu (AES) wrote: >In article <geh9sa$fbs$1 at smc.vnet.net>, dch888 ><dch888 at googlemail.com> wrote: >>>Another answer is that Mathematica *should* understand the syntax >>>with ellipsis-- and indeed it can with the facilities of David >>>Park's Presentations application package. >One has to be careful about the use and interpretation of ellipses. >For example the Mathematica documentation for Compound Expression >says that >expr_1 ; expr_2 ; =C2=8A evaluates the expr_i in turn, giving the last >one as the result. >Would this statement, interpreted very literally using a precise >definition of the ellipsis symbol, cover both >expr_1 ; expr_2 ; expr_3 ; expr_4 ; >and >expr_1 ; expr_2 ; expr_3 ; expr_4 >or just one of these? (Which one?) If an ellipsis were a symbol Mathematica understood and could be used to replace some of the parts in your examples, I would expect your first example to be written expr_1 ; ... expr_4 ; and your second example to be written as expr_1 ; ... expr_4 So there would be no ambiguity. But I doubt even if Mathematica understood an ellipsis, these would be allowed constructs. Consider a rather simple usage of the ellipsis in mathematics, i.e., 1+2+3+ ... +10+11+12 or 1,2,3, ... 12 The first would be interpreted as the sum of the first 12 natural numbers and the second a list of the first 12 natural numbers. Neither is really a sequence of expressions as is the case for your examples. >_Is there_ a precise definition of the ellipsis symbol? (in English, >or in Mathematica) Certainly, there is a definition in English. But precision isn't well defined when it comes to English definitions. As for Mathematica, there should be no expectation of a definition other than the English definition since this isn't allowed Mathematica syntax.