  We propose an approach to decomposing a thematic information stream into
principal components. Each principal component is related to a narrow topic
extracted from the information stream. The essence of the approach arises from
analogy with the Fourier transform. We examine methods for analyzing the
principal components and propose using multifractal analysis for identifying
similar topics. The decomposition technique is applied to the information
stream dedicated to Brexit. We provide a comparison between the principal
components obtained by applying the decomposition to Brexit stream and the
related topics extracted by Google Trends.
