On the duality of specific early and late fusion strategies

In this paper, we prove that specific early and specific late fusion strategies are interchangeable. In the case of the late fusion, we consider not only linear but also nonlinear combinations of scores. Our findings are important from both theoretical and practical (applied) perspectives. The duality of specific fusion strategies also answers the question why in the literature the experimental results for both early and late fusion are often similar. The most important aspect of our research is, however, related to the presumable drawbacks of the aforementioned fusion strategies. It is an accepted fact that the main drawback of the early fusion is the curse of dimensionality (generation of high dimensional vectors) whereas the main drawback of the late fusion is its inability to capture correlation between feature spaces1. Our proof on the interchangeability of specific fusion schemes undermines this belief. Only one of the possibilities exists: either the late fusion is capable of capturing the correlation between feature spaces or the interaction between the early fusion operators and the similarity measurements decorrelates feature spaces.