Cyclic computational graphs with Tensorflow or The

Question

Both TensorFlow and Theano do not seem to support cyclic computational graphs, cyclic elements are implemented as recurrent cells with buffer and unrolling (RNN / LSTM cells), but this limitation is mostly related with the computation of back-propagation. I don't have a particular need for computing back-propagation but just the forward propagations.

Is there a way to ignore this limitation, or perhaps just to break down arbitrary computational graphs in acyclic components?

Answer 1

TensorFlow does support cyclic computation graphs. The tf.while_loop() function allows you to specify a while loop with arbitrary subgraphs for the condition and the body of the loop, and the runtime will execute the loop in parallel. The tf.scan() function is a higher-level API that is similar to Theano's theano.scan() function. Both allow you to loop over tensors of dynamic size.