I am trying to implement Neural Network in MapReduce. Apache mahout is reffering this paper <http://www.cs.stanford.edu/people/ang/papers/nips06-mapreducemulticore.pdf>
Neural Network (NN) We focus on backpropagation By defining a network structure (we use a three layer network with two output neurons classifying the data into two categories), each mapper propagates its set of data through the network. For each training example, the error is back propagated to calculate the partial gradient for each of the weights in the network. The reducer then sums the partial gradient from each mapper and does a batch gradient descent to update the weights of the network. Here <http://homepages.gold.ac.uk/nikolaev/311sperc.htm> is the worked out example for gradient descent algorithm. Gradient Descent Learning Algorithm for Sigmoidal Perceptrons <http://pastebin.com/6gAQv5vb> 1. Which is the better way to parallize neural network algorithm While looking in MapReduce perspective? In mapper: Each Record owns a partial weight(from above example: w0,w1,w2),I doubt if w0 is bias. A random weight will be assigned initially and initial record calculates the output(o) and weight get updated , second record also find the output and deltaW is got updated with the previous deltaW value. While coming into reducer the sum of gradient is calculated. ie if we have 3 mappers,we will be able to get 3 w0,w1,w2.These are summed and using batch gradient descent we will be updating the weights of the network. 2. In the above method how can we ensure that which previous weight is taken while considering more than 1 map task.Each map task has its own weight updated.How can it be accurate? [image: enter image description here] 3. Where can I find backward propogation in the above mentioned gradient descent neural network algorithm?Or is it fine with this implementation? 4. what is the termination condition mensioned in the algorithm? Please help me with some pointers. Thanks in advance. -- *Thanks & Regards * *Unmesha Sreeveni U.B* *Hadoop, Bigdata Developer* *Centre for Cyber Security | Amrita Vishwa Vidyapeetham* http://www.unmeshasreeveni.blogspot.in/
