Chapter 6

The Nature of Information

What is information? We have already asserted that it is a profound, primitive (i.e.,

irreducible) concept. Dictionary definitions include “(desired) items of knowledge”;

for example, one wishes to know the length of a piece of wood. It appears to be

less than a foot long, so we measure it with our desktop ruler marked off in inches,

with the result, let us say, “between six and seven inches”. This result is clearly

an item of desired knowledge, hence information. We shall return to this example

later. Another definition is “fact(s) learned about something”, implying that there is

a definable object to which the facts are related, suggesting the need for context and

meaning. A further definition is “what is conveyed or represented by a particular

arrangement of things”; the dots on the head of a matrix printer shape a letter, the bar

code on an item of merchandise represents facts about the nature, origin, and price

of the merchandise, and a sequence of letters can convey a possibly infinite range

of meanings. A thesaurus gives as synonyms “advice, data, instruction, message,

news, report”. Finally, we have “a mathematical quantity expressing the probability

of occurrence of a specific sequence of symbols or impulses as against that of other

sequences (i.e., messages)”. This definition links the quantification of information

to a probability, which, as we shall see, plays a major rôle in the development of the

subject.

We also note that “information science” is defined as the “study of processes

for storing and retrieving information”, and “information theory” is defined as the

“quantitative study of transmission processes for storing and retrieving of information

by signals”; that is, it deals with the mathematical problems arising in connexion with

the storage, transformation, and transmission of information. This forms the material

for Chap. 7. Etymologically, the word “information” comes from the Latin forma,

form, from formare, to give shape to, to describe.

Most information can be reduced to the response, or series of responses, to a

question, or series of questions, admitting only yes or no as an answer. We call these

yes/no, or dichotomous, questions. Typically, interpretation depends heavily on con-

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J. Ramsden, Bioinformatics, Computational Biology,

https://doi.org/10.1007/978-3-030-45607-8_6

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