Bidirectional Propagation

This repo contains code to reproduce experiments in paper "Bidirectional Backpropagation: Towards Biologically Plausible Error Signal Transmission in Neural Networks" (https://arxiv.org/abs/1702.07097)

This code and readme is copied and modified based on https://github.com/anokland/dfa-torch (Direct Feedback Alignment using Torch) Supported datasets are {Cifar10, MNIST}

Dependencies

• Torch (http://torch.ch)
• "DataProvider.torch" (https://github.com/eladhoffer/DataProvider.torch) for DataProvider class.
• "cudnn.torch" (https://github.com/soumith/cudnn.torch) for faster training. Can be avoided by changing "cudnn" to "nn" in models.
• "dpnn" (https://github.com/Element-Research/dpnn) for maxnorm constraints on weights
• "unsup" (https://github.com/koraykv/unsup) for whitening of data
• "mnist" (https://github.com/andresy/mnist) for MNIST data set

To install all dependencies (assuming torch is installed) use:

luarocks install https://raw.githubusercontent.com/eladhoffer/eladtools/master/eladtools-scm-1.rockspec
luarocks install https://raw.githubusercontent.com/eladhoffer/DataProvider.torch/master/dataprovider-scm-1.rockspec
luarocks install dpnn
luarocks install unsup
luarocks install https://raw.github.com/andresy/mnist/master/rocks/mnist-scm-1.rockspec

Training

To train and evaluate the Bidirectional Direct Feedback Alignment model on MNIST and CIFAR10 datasets,

th Main.lua -dataset MNIST -network mlp.lua -LR 1e-4

or,

th Main.lua -dataset Cifar10 -network conv.lua -LR 5e-5

Additional flags

Flag	Default Value	Description
modelsFolder	./Models/	models Folder
network	mlp.lua	model file - must return valid network.
criterion	bce	criterion, ce(cross-entropy) or bce(binary cross-entropy)
eps	0	adversarial regularization magnitude (fast-sign-method a.la Goodfellow)
dropout	0	1=apply dropout regularization
batchnorm	0	1=apply batch normalization
nonlin	tanh	nonlinearity (tanh,sigm,relu)
num_layers	2	number of hidden layers (if applicable)
num_hidden	800	number of hidden neurons (if applicable)
bias	1	0=do not use bias
rfb_mag	0	random feedback magnitude, 0=uniform distribution in [-1/sqrt(fanout),1/sqrt(fanout)], X=uniform distribution in [-X,X], X=1 works fine with SGD
LR	0.0001	learning rate
LRDecay	0	learning rate decay (in # samples)
weightDecay	0	L2 penalty on the weights
momentum	0	momentum
batchSize	64	batch size
optimization	rmsprop	optimization method(sgd,rmsprop,adam etc)
epoch	300	number of epochs to train (-1 for unbounded)
epoch_step	-1	learning rate step, -1 for no step, 0 for auto, >0 for multiple of epochs to decrease
gradient	dfa	gradient for learning, bp(back-prop), fa(feedback-alignment) or dfa(direct feedback-alignment)
maxInNorm	400	max norm on incoming weights
maxOutNorm	400	max norm on outgoing weights
accGradient	0	1=accumulate normal and adversarial gradient (if eps>0)
threads	8	number of threads
type	cuda	float or cuda
devid	1	device ID (if using CUDA)
load	none	load existing net weights
save	time-identifier	save directory
dataset	MNIST	dataset - Cifar10, Cifar100, STL10, SVHN, MNIST
datapath	./Datasets/	data set directory
normalization	scale	scale(between 0 and 1), simple(whole sample,mean=0,std=1), channel(by image channel), image(mean and std images)
format	rgb	rgb or yuv
whiten	false	whiten data
augment	false	augment training data
preProcDir	./PreProcData/	data directory for pre-processing (means,Pinv,P)
validate	false	use validation set for testing instead of test set
visualize	0	1=visualizing results