  Information exploration tasks are inherently complex, ill-structured, and
involve sequences of actions usually spread over many sessions. When exploring
a dataset, users tend to experiment higher degrees of uncertainty, mostly
raised by knowledge gaps concerning the information sources, the task, and the
efficiency of the chosen exploration actions, strategies, and tools in
supporting the task solution process. Provided these concerns, exploration
tools should be designed with the goal of leveraging the mapping between user's
cognitive actions and solution strategies onto the current systems' operations.
However, state-of-the-art systems fail in providing an expressive set of
operations that covers a wide range of exploration problems. There is not a
common understanding of neither which operators are required nor in which ways
they can be used by explorers. In order to mitigate these shortcomings, this
work presents a formal framework of exploration operations expressive enough to
describe at least the majority of state-of-the-art exploration interfaces and
tasks. We also show how the framework leveraged a new evaluation approach,
where we draw precise comparisons between tools concerning the range of
exploration tasks they support.
