Abstract:
Red and blue galaxies are traditionally classified using some specific cuts in colour or other galaxy properties, which are
supported by empirical arguments. The vagueness associated with such cuts are likely to introduce a significant contamination
in these samples. Fuzzy sets are vague boundary sets that can efficiently capture the classification uncertainty in the absence of
any precise boundary. We propose a method for classification of galaxies according to their colours using fuzzy set theory. We
use data from the Sloan Digital Sky Survey (SDSS) to construct a fuzzy set for red galaxies with its members having different
degrees of ‘redness’. We show that the fuzzy sets for the blue and green galaxies can be obtained from it using different fuzzy
operations. We also explore the possibility of using fuzzy relation to study the relationship between different galaxy properties
and discuss its strengths and limitations
