be more careful about using associate_variable -- it
could be either a variable or a distribution -- it
should be renamed to "owner" throughout.
attached are diffs for AbstractConditionalVariable.java
and IntegralCache.java which implement part of the
required functionality. these diffs were made in the
process of debugging a problem with handling
IndexedDistribution in lamba messages calculation. it
may be that the real problem was the presence of the
obsolete file ID_GD_D.java, so it's not clear that we
really want to apply these diffs to the production
version. still, here they are for reference.