  Many studies have been conducted so far to build systems for recommending
fashion items and outfits. Although they achieve good performances in their
respective tasks, most of them cannot explain their judgments to the users,
which compromises their usefulness. Toward explainable fashion recommendation,
this study proposes a system that is able not only to provide a goodness score
for an outfit but also to explain the score by providing reason behind it. For
this purpose, we propose a method for quantifying how influential each feature
of each item is to the score. Using this influence value, we can identify which
item and what feature make the outfit good or bad. We represent the image of
each item with a combination of human-interpretable features, and thereby the
identification of the most influential item-feature pair gives useful
explanation of the output score. To evaluate the performance of this approach,
we design an experiment that can be performed without human annotation; we
replace a single item-feature pair in an outfit so that the score will
decrease, and then we test if the proposed method can detect the replaced item
correctly using the above influence values. The experimental results show that
the proposed method can accurately detect bad items in outfits lowering their
scores.
