Post-lunch, the final day of Web Science 2016 continues with a keynote by Andrew Tomkins, whose focus is on the dynamics of choice in online environments. He begins by highlighting R. Duncan Luce's work, including his Axiom of Choice, but also points out the subsequent work that has further extended the methods for analysing discrete choice. Today, the most powerful models are mathematically complex and computationally intractable, as well as requiring sophisticated external representations of dependence.
From this work it has become clear that the Axiom of Choice holds only under relatively select conditions. Contextual data is of great importance here, and additional approaches to modelling general behaviour of discrete choice are required. The Randomised Utility Model, for instance, assigns a random utility value to each available choice, and in an ideal world users would then select the item with maximum utility; but because of existing preferences real-world users will deviate from such choices.