I am reading a section in a book about translation. The formula below is given as a mathematical way to calculate word translation entropy. So for a source token
s and all available translations
t_i...n one could calculate the word translation entropy of
s like so.
But I am confused about the raised star. The accompanied text reads:
Word translation entropy H(s) is the sum over all observed word translation probabilities (i.e. expectations) of a given ST word s into TT words t_i...n multiplied with their information content.
So I am assuming that it is multiplication. But why is it a raised star in superscript? Why isn't it written it normally, inline? (I am not at all a mathematician, so apologies if this is a basic notation question.)
The formula can be found on p. 31 in the following book.
Carl, M., Schaeffer, M. J., & Bangalore, S. (2016). The CRITT Translation Process Research Database. In M. Carl, S. Bangalore, & M. J. Schaeffer (Eds.), New Directions in Empirical Translation Process Research (pp. 13–54). Cham, Switzerland: Springer International Publishing.