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**To**:*math-font-discuss@cogs.susx.ac.uk***Subject**:**Re: \ell****From**:*Martin Ward <Martin.Ward@durham.ac.uk>***Date**: Thu, 5 Aug 93 15:54:48 BST

>I don't understand the purpose of the \ell glyph from a >mathematician's point of view. My conjecture: In ancient times >mathematicians had to use typewriters where lowercase Latin l was >indistinguishable from the numeral 1. In ancient times mathematicians used pencils, quill pens, slates, clay tablets... I still find that the best tools for doing mathematics are a pencil and paper. I use \ell to denote the length of a sequence, for example: ... the length of the sequence $L=\langle l_1, l_2, \dots l_n \rangle$ is denoted $\ell(L)$ ... (see: ``Abstracting a Specification from Code'', M. Ward, Journal of Software Maintenance: Research and Practice, Vol 5, 1993, pp 101-122, photocopies supplied on request!) Mathematician's are always searching around for new symbols. Some of these are constructed by starting with a letter and writing it in a different way (epsilon used as set membership, the so-called ``blackboard bold'' N, Z, Q, R and C used to represent sets of numbers, \Sigma used as a summation sign, \partial, which is a variant of either \delta or d, for PDEs etc.) Sometimes these symbols take on a new meaning of their own, and become widely adopted. The historical source is no guide to how these symbols should be typeset _now_: consider the integration symbol \int which was originally a ``long s'' representing ``summation''. Since we no longer use ``long s'' we should replace \int by the letter s right? :-) Martin.