In- and out-of-table operations
In Lace there are a number of operations that seem redundant. Why is there
simulate
and draw
; predict
and impute
? Why is there surprisal
when
one can simple compute -logp
? The answer is that the are in-table operations
and out-of-table (or hypothetical) operations. In-table operations use the
probability distribution at a certain cell in the PCC table, while out-of-table
operations do not take table location, and thus category and view assignments
into account. Hypothetical operations must marginalize over assignments.
Here is a table listing in-table and hypothetical operations.
Purpose | In-table | Hypothetical |
---|---|---|
Draw random data | draw | simulate |
Compute likelihood | (-) surprisal | logp |
Find argmax of a likelihood | impute | predict |