And then they run out of Latin letters so they switch to Greek. Then they run out of Greek letters so they switch to Hebrew...<p>You have to remember that math is written for the sake of mathematicians&#x27; brains, not for the sake of dumb machines which accept only linear strings of a limited character set through a teletype. A mathematician can look at a formula and subconsciously break it down into constituent parts based on its <i>shape</i>. Multi-letter (word? phrase?) variable names would only serve to add unnecessary clutter and obscure the shape of the formula. Meaningfulness of names is a secondary concern, if it is a concern at all; meaning can be established in the text surrounding the formulas or equations; and if things indeed get too complex for a set of a few formulas, the option is always there to switch representations -- to computer code or pseudocode.