Based on the "otherness" definition, information is assumed to be made up of "dimensions". Consequently, mathematical description of information is realized, and basic operations on information are also realizable. Hence, in IA subspace, information may be valued; the process of IA may be described quantificationally and mathematically. The IAC is brought forward to evaluate the IA process, and the evaluating result is used to ameliorate the IA process.
Portfolio theory of information retrieval
