According to Shannon's classical information theory [19] information is measured by the reduction of uncertainty and the latter is measured by  entropy  . This theory is concerned with the transmission of symbols from a finite alphabet. The uncertainty concerns the question which symbol is sent and the information is given by a probabilistic model of the transmission channel and the symbol observed at the output of the channel. This leads to a statistical communication theory which is still the main subject of communication theory today.
['Jürg Kohlas', 'Cesar Schneuwly']
Information Algebra