Information System Project Manager Review Summary (1)

Chapter 1 Informatization and Information Systems

1.1 Information system and informatization

• Information is an objective thing, and like materials and energy, it is the basic resource of society. However, rational knowledge of information is only a few decades old. In 1948, American scientist Claude E. Shannon put forward information theory on the basis of in-depth research on communication theory (the paper "Mathematical Theory of Communication" was published in October 1948. " as the beginning of modern information theory research.)
• Information theory, cybernetics and systems theory are called the "three theories" of modern science.

1.1.1 The basic concept of information

• Shannon pointed out that information is what can be used to eliminate uncertainty.
• The unit of information is bits.
• The amount of information of 1 bit, in the simplest case with a degree of variability of 2, is the amount of information required to eliminate either-or uncertainty.
• Shannon introduced thermodynamic entropy to information theory. Information is a measure of the degree of order of the system, which is expressed as negative entropy. The calculation formula is as follows:
  $$H(x)=-\sum{P(X_i)log_2P(X_i)}$$
• In the formula, x _i represents the ith state among the n states, P(x _i ) represents the probability of the occurrence of the first state, and H(x) represents the amount of information required to eliminate the uncertainty of the system, that is, with Negative entropy in bits.
  
  1. characteristics of information

(1) Objectivity
(2) Universality
(3) Infiniteness
(4) Dynamics
(5) Relativity
(6) Dependency
(7) Transformation
(8) Transitivity
(9) Hierarchy
(10) Systematic
(11) Convertibility