lamblin/Theano — comment on commit bd27a4624cd44a2c36eb721cfd5f4e5f221bb60b
File: theano/gof/graph.py line 173
By lamblin:

"strict" has 2 purposes here:
- Ensure that the node will be able to be rebuilt, and will have the same output type as before, and that is clearly the case since we have change the Type of potentially offending inputs.
- As in "filter", ensure that we are not risking changing the value of the data itself (by loss of precision, losing sparsity information, and so on). Since filter_variable only allows for really close Types to be converted to each other (Types that may be merged together in the future), I think it is safe.