# Log 02-19-2013

Writing this post-hoc. Apparently today I wrote a long-ass summary of progress on the very lazy evaluation project so far (which I’ve been thinking of as “probabilistic abstractions”). This includes the notion of a probabilistic abstraction, of a $\Pi$-system, of a valid abstraction of a function, and also efficiently algorithms for subsampling $\Pi$-systems that are tree-structured, as well as a criterion for the optimal choice of which to include among a collection of random variables, if we can only include a limited number $k$ of them (it turns out the answer is to take the ones with minimum marginal entropy).