  We study source coding in the presence of side information, when the system
can take actions that affect the availability, quality, or nature of the side
information. We begin by extending the Wyner-Ziv problem of source coding with
decoder side information to the case where the decoder is allowed to choose
actions affecting the side information. We then consider the setting where
actions are taken by the encoder, based on its observation of the source.
Actions may have costs that are commensurate with the quality of the side
information they yield, and an overall per-symbol cost constraint may be
imposed. We characterize the achievable tradeoffs between rate, distortion, and
cost in some of these problem settings. Among our findings is the fact that
even in the absence of a cost constraint, greedily choosing the action
associated with the `best' side information is, in general, sub-optimal. A few
examples are worked out.
