Let S = {( 1,y1),...,( n,yn)}.

Learning byassociating ambiguously labeled images.

Africa pose, partial view, color diapers The Americas vs. Africa pose, color, partial view pet foods Asia vs.

Although the importance of feedback in neural information processing has been widely recognized in the field, the detailed mechanism of how it works remains largely unknown. Here, we investigate the role of feedback in hierarchical information retrieval.