Rprop
{{Not to be confused with|Stochastic gradient descent#RMSProp}}
{{Short description|Learning heuristic for supervised learning}}
Rprop, short for resilient backpropagation, is a learning heuristic for supervised learning in feedforward artificial neural networks. This is a first-order optimization algorithm. This algorithm was created by Martin Riedmiller and Heinrich Braun in 1992.Martin Riedmiller und Heinrich Braun: Rprop - A Fast Adaptive Learning Algorithm. Proceedings of the International Symposium on Computer and Information Science VII, 1992
Similarly to the Manhattan update rule, Rprop takes into account only the sign of the partial derivative over all patterns (not the magnitude), and acts independently on each "weight". For each weight, if there was a sign change of the partial derivative of the total error function compared to the last iteration, the update value for that weight is multiplied by a factor η−, where η− < 1. If the last iteration produced the same sign, the update value is multiplied by a factor of η+, where η+ > 1. The update values are calculated for each weight in the above manner, and finally each weight is changed by its own update value, in the opposite direction of that weight's partial derivative, so as to minimise the total error function. η+ is empirically set to 1.2 and η− to 0.5.{{cn|date=August 2022}}
Rprop can result in very large weight increments or decrements if the gradients are large, which is a problem when using mini-batches as opposed to full batches. RMSprop addresses this problem by keeping the moving average of the squared gradients for each weight and dividing the gradient by the square root of the mean square.{{cn|date=June 2024}}
RPROP is a batch update algorithm. Next to the cascade correlation algorithm and the Levenberg–Marquardt algorithm, Rprop is one of the fastest weight update mechanisms.{{cn|date=August 2022}}
Variations
Martin Riedmiller developed three algorithms, all named RPROP. Igel and Hüsken assigned names to them and added a new variant:Christian Igel and Michael Hüsken. [http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.17.1332 Improving the Rprop Learning Algorithm]. Second International Symposium on Neural Computation (NC 2000), pp. 115-121, ICSC Academic Press, 2000
- RPROP+ is defined at [http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.21.1417 A Direct Adaptive Method for Faster Backpropagation Learning: The RPROP Algorithm].Martin Riedmiller and Heinrich Braun. [http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.21.1417 A direct adaptive method for faster backpropagation learning: The Rprop algorithm]. Proceedings of the IEEE International Conference on Neural Networks, 586-591, IEEE Press, 1993
- RPROP− is defined at [http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.27.7876 Advanced Supervised Learning in Multi-layer Perceptrons – From Backpropagation to Adaptive Learning Algorithms]. Backtracking is removed from RPROP+.Martin Riedmiller. [http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.27.7876 Advanced supervised learning in multi-layer perceptrons - From backpropagation to adaptive learning algorithms]. Computer Standards and Interfaces 16(5), 265-278, 1994
- iRPROP− is defined in [http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.21.3428 Rprop – Description and Implementation Details]Martin Riedmiller. [http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.21.3428 Rprop – Description and Implementation Details]. Technical report, 1994 and was reinvented by Igel and Hüsken. This variant is very popular and most simple.
- iRPROP+ is defined at [http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.17.1332 Improving the Rprop Learning Algorithm] and is very robust and typically faster than the other three variants.
References
{{Reflist}}
External links
- [http://www.ias.informatik.tu-darmstadt.de/Research/RpropToolbox Rprop Optimization Toolbox]
- [http://www.mathworks.com/matlabcentral/fileexchange/32445-rprop Rprop training for Neural Networks in MATLAB]