on is the indexing of very large databases, such as the inventories of nucleotide sequences in biology. Golomb-Rice codes are also used in sound compression standards (see Appendix G). Arithmetic coding In static codes (Shannon-Fano, Huffman, block, and integer codings), it is implicitly assumed that the source characteristics (events and probabilities) are known, with the exception of integer coding, which only requires knowledge of the most likely events. In any case, these codes are fixed and optimized once and for all, SO this approach is called defined-word coding. In the general case, one may not have such a prior knowledge. It is also possible that the source properties change from time to time (nonstationary source), in which case static codes lose their optimality or become inadequate. Nontypical English texts, such as those analyzed in Chapter 9 (Table 9.2), provide an illustrative example of deviation from the stationary source reference.6 As we saw in that chapter, we 6 A famous example of a very unusual English-text source is the 1939 novel Gadsby (E. V. Wright), which, in over 50 000 words, does not contain any character E whatsoever! Here is an extract from page If youth, throughout all history, had a champion to stand up for it; to show a doubting world that a child think; and, possibly, do it practically; you wouldn't constantly run across folks today who claim that "a child don't know anything." A child's brain starts functioning at birth; and has, amongst its many infant Integer, arithmetic, and adaptive coding can use universal codebooks, which contain libraries of best codes for a variety of sources, such as text, programming-language codes, or datafiles, or a statistical mix of all possible combinations thereof. But the codebook approach is inadequate if the source under investigation escapes any of these known types. Static coding is, therefore, intrinsically limited, although it is most convenient because the symbol or codeword correspondence only requires a one-time calculation and optimi