Intuitively, this distribution should assign high probability to good specification trees that can produce C++ code that reads all input examples without errors, we therefore define P (t) as follows: 5 1 the input parser of tree t reads all input examples without error otherwise where Z is a normalization factor and is empirically set to 10 −6 .
p (•) treats all specification trees that pass the input example test as equally probable candidates and inhibits the model from generating trees which fail the test.