Seee the paper at: https://arxiv.org/abs/1701.03441

Simplifications of Gate Units for Long Short-term Memory (LSTM):

Case1): No input signal

Case2): No Input signal + No bias

Case3): No input signal + No hidden unit

Implementation environment: keras2.06 + Theano0.9 + wind10 + Cuda8.0 + cudnn5.1

This has been tested on numerous datasets including MNIST, IMDB, RNT, PennTree bank, etc.