Classical definitions of complementarity are based on cross price elasticities, and so they do not apply, for example, when goods are free. This context includes many relevant cases such as online newspapers and public attractions. We look for a complementarity notion that does not rely on price...

We propose a novel method to model an agent who is imperfectly attentive in the sense that she may consider only some of the alternatives available. Our methodology departs from the standard 'revealed preference' one: we make plausible assumptions on the values to the imperfectly attentive agent...