The file attached to this record is the Publisher's version.Spectral analysis as a powerful mean to identify the characteristics of data
series is introduced in this paper. The problems requiring further explorations in
grey system theory are also identified. This includes discrimination of various
factors of a data sequence in frequency domain, spectral analysis of various
sequence operators, the synthesis axiom of degree of greyness for “multiplication”
and “division” etc. Further, how to select and test a grey prediction model? How
to select and test an inverse grey incidence analysis model? The test rules and
criteria of grey clustering evaluation models, etc
