4.2.3 Thesaurus support

The thesaurus would allow the math search system designers to define various terms not only in terms of equivalent synonyms, but also as full-fledged queries (i.e., an expression involving Boolean and/or proximity operators). For example, it was mentioned earlier that markup such as BesselJ (and BesselI, BesselK, BesselH etc.) helps in semantics and formatting matters. Should a user enter Bessel as a keyword, all those markup words (BesselJ, BesselI, etc.) will not be recognized as matches of Bessel. However, if an entry for Bessel is defined in the thesaurus, where Bessel is made to stand for

$$\texttt{(Bessel OR BesselJ OR BesselY \ldots)},$$

a thesaurus lookup will cause the keyword Bessel to be replaced by its thesaurus entry, and the markup is then guaranteed to be matched.

Note, however, that such a thesaurus cannot handle mathematical equivalences that involve formulas.