A symbol’s self-information falls to zero as its probability approaches certainty.

Evidence

For any of the eight symbols shown in Table 7.8, the self-information is 3 bits because they all have the same probability. However, if the probabil­ ity of a particular symbol was one, i.e., it was like our repeating “h” dis­ cussed earlier, the self-information would be zero. — David Howard, Jamie Angus, coustics and Psychoacoustics, 2613

Categorization

• XREF: Connects back to the earlier repeating-”h” redundancy example from prior chapters on the entropy stage.