Organizations: INSA Lyon, CNRS, Ecole Centrale de Lyon, Universite Claude Bernard Lyon 1, Université Lumière Lyon 2, LIRIS, UMR5205, , Villeurbanne, 69621, France
This paper introduces Growing Networks with Autonomous Pruning (GNAP) for image classification. Unlike traditional convolutional neural networks, GNAP change their size, as well as the number of parameters they are using, during training, in order to best fit the data while trying to use as few parameters as possible. This is achieved through two complementary mechanisms: growth and pruning. GNAP start with few parameters, but their size is expanded periodically during training to add more expressive power each time the network has converged to a saturation point. Between these growing phases, model parameters are trained for classification and pruned simultaneously, with complete autonomy by gradient descent. Growing phases allow GNAP to improve their classification performance, while autonomous pruning allows them to keep as few parameters as possible. Experimental results on several image classification benchmarks show that our approach can train extremely sparse neural networks with high accuracy. For example, on MNIST, we achieved 99.44% accuracy with as few as 6.2k parameters, while on CIFAR10, we achieved 92.2\ accuracy with 157.8k parameters.
Figures & tables
Figure 1: The overall network architecture of GNAP ( conv : convolution layer, pool : pooling layer, cat : feature map concatenation, fc : fully-connected layer). Each layer may be (sparsely) connected to all preceding layers. Each block may contain one or several convolution layers with the same feature map size. During training, structured (kernel) pruning or unstructured pruning is performed and layers are grown and added repeatedly.
Model
block 1
block 2
block 3
FC
GNAP (MNIST)
10
10
10
GNAP (CF10)
64, 64, 64
128, 128, 128
256, 256, 256
10
GNAP (CF100)
64, 64, 64
128, 128, 128
256, 256, 256
100
NAP (m1) (MNIST)
10
10
10
NAP (m2) (MNIST)
100
100
10
NAP (m3) (CF10)
64
128
10
Table 1: Initial architectures of the different tested models obtaining different accuracy-complexity trade-offs. The numbers indicate the size of the layers (i.e. the number of neurons/channels).
Method
Accuracy
Links
Weights
NAP-U (m1)
0.9875
± 0.0008
5762
± 437
5762
± 437
NAP-U (m2)
0.9938
± 0.0008
9264
± 2202
9264
± 2202
GNAP-U (rand)
0.9943
± 0.0004
6154
± 291
6154
± 291
GNAP-U (ortho)
0.9944
± 0.0004
6234
± 203
6234
± 203
NAP-S (m1)
0.9823
± 0.0023
5409
± 1388
5928
± 1482
NAP-S (m2)
0.9923
± 0.0012
21003
± 10068
28533
± 11678
Table 2: Performance on MNIST.
Method
Accuracy
Links
Weights
NAP-U (m4)
0.8763
± 0.0055
235655
± 67951
235655
± 67951
NAP-U (m5)
0.8849
± 0.0107
245168
± 68530
245168
± 68530
NAP-U (m6)
0.9162
± 0.0024
696837
± 116179
696837
± 116179
GNAP-U (rand)
0.9245
± 0.0046
179979
± 26074
179979
± 26074
GNAP-U (ortho)
0.9222
± 0.0041
157765
± 18620
157765
± 18620
NAP-S (m4)
0.8802
± 0.0049
99097
± 38844
340501
± 65564
Table 3: Performance on CIFAR10.
Method
Accuracy
Links
Weights
NAP-U (m7)
0.5583
± 0.0173
393330
± 121100
393330
± 121100
NAP-U (m8)
0.6408
± 0.0158
410827
± 118481
410827
± 118481
GNAP-U (rand)
0.6692
± 0.0106
207289
± 59319
207289
± 59319
GNAP-U (ortho)
0.6656
± 0.0086
179857
± 28182
179857
± 28182
NAP-S (m7)
0.5085
± 0.0124
231668
± 3532
247850
± 4221
NAP-S (m8)
0.5965
± 0.0141
235029
± 34575
461149
± 142521
Table 4: Performance on CIFAR100.
Method
Accuracy
Weights
Base architecture
SimpleNet [ 7 ]
0.9198
310000
SNIP [ 11 ]
0.9272
± 0.0018
186013
ResNet32
SNIP [ 11 ]
0.7612
± 0.2196
410968
VGG19
GraSP [ 22 ]
0.9286
± 0.0019
186013
ResNet32
GraSP [ 22 ]
0.9216
± 0.0014
410968
VGG19
SRatio [ 19 ]
0.9185
± 0.0016
93006
ResNet32
Table 5: Comparison with state-of-the-art sparse CNN on CIFAR10. Our approach outperforms most methods combining the criteria of accuracy and number of weights without the dependence on a pre-defined initial dense network.
Method
Accuracy
Weights
Base architecture
SimpleNet [ 7 ]
0.6468
310000
SNIP [ 11 ]
0.6554
± 0.0026
93006
ResNet32
SNIP [ 11 ]
0.2534
± 0.0916
410968
VGG19
GraSP [ 22 ]
0.6584
± 0.0014
93006
ResNet32
GraSP [ 22 ]
0.6584
± 0.0036
205484
VGG19
SRatio [ 19 ]
0.6708
± 0.0041
93006
ResNet32
Table 6: Comparison with state-of-the-art sparse CNN on CIFAR100. Our approach outperforms most methods combining the criteria of accuracy and number of weights without the dependence on a pre-defined initial dense network.
Figure 2: The evolution of the different losses and number of open gates during training of our GNAP model (here GNAP-U on CIFAR10) (Please note that the scale for the number of open gates is logarithmic).
Figure 3: The evolution of the accuracy vs. number of parameters. Each curve is a snapshot of the model before a given growing phase (e.g. "0" is the model before the first growing phase). The points of a curve represent different gate thresholds γ at inference.
Figure 4: The evolution of links (open gates) of our GNAP model during training (here GNAP-U on CIFAR10). Numbers indicate training epochs. A pixel at row i and column j represents the link going from neuron j to neuron i. The intensity of a pixel represents the proportion of open gates between two neurons/feature maps.
Neural network pruning reduces model size by removing less important parameters while aiming to preserve predictive performance. Although the Lottery Ticket Hypothesis (LTH) shows that sparse subnetworks can match dense networks when trained from suitable initializations, its iterative pruning procedure requires multiple complete training cycles. This work evaluates progressive magnitude-based pruning as a single-cycle alternative. The method gradually increases sparsity during training using a linear schedule and updates pruning masks based on active weight magnitudes. We conduct systematic experiments on CIFAR-10 and MNIST across ResNet, VGG-style, and LeNet architectures, comparing the proposed method with representative iterative and initialization-based pruning baselines, including LTH, SNIP, and GraSP. On CIFAR-10, the method achieves 95.12% accuracy on ResNet-18 at 72.9% sparsity, compared with 90.5% reported for LTH. At extreme sparsity, it achieves 93.13% accuracy on a VGG-like architecture at 97% sparsity, compared with approximately 92.0% for SNIP, and 93.44% accuracy on VGG-19 at 97.97% sparsity, compared with 92.19% for GraSP at 98% sparsity. A sparsity-accuracy analysis on ResNet-18 further shows that accuracy remains within 0.1 percentage points of the dense baseline across 70--85% sparsity. These results indicate that progressive magnitude-based pruning provides an effective single-cycle approach for neural network sparsification under the evaluated settings.
Romana Qureshi, Hafida Benhidour, Said Kerrache +1
Department of Computer Science, King Saud University, Riyadh, Saudi Arabia
Network pruning is used to reduce inference latency and power consumption in large neural networks. However, most methods focus on empirical results at the expense of understanding the pruning process. We introduce Hyperflux, a novel L0 method which models pruning as a continuously evolving system determined by flux, the gradient response to a weight's removal, and pressure, a global regularization driving weights toward pruning. By exploiting this model, Hyperflux's pruning behavior becomes understandable at both microscopic (weight regrowth/pruning) and macroscopic (sparsity convergence, etc.) levels. We also introduce a novel pressure scheduler that reliably targets desired sparsities. Hyperflux achieves competitive results with ResNet-50, VGG-19 and DeiT-T/S on CIFAR-10, CIFAR-100 and ImageNet datasets.
Eugen Barbulescu, Antonio Alexoaie, Lucian Busoniu
Department of Computer Science Technical University of Cluj-Napoca · Department of Automation Technical University of Cluj-Napoca
I propose the Random Cloud method, a training-free approach to neural architecture search that discovers minimal feedforward network topologies through stochastic exploration and progressive structural reduction. Unlike post-training pruning methods that require a full train-prune-retrain cycle, this method evaluates randomly initialized networks without backpropagation, progressively reduces their topology, and only trains the best minimal candidate at the end. I evaluate on 7 classification benchmarks against magnitude pruning and random pruning baselines. The Random Cloud matches or outperforms both baselines in 6 of 7 datasets, achieving statistically significant improvements on Sonar (+4.9pp accuracy, p=0.017 vs magnitude pruning) with 87% parameter reduction. Crucially, the method is faster than both pruning baselines in 4 of 5 datasets (0.67--0.94× the cost of full training), since it avoids training the full-size network entirely.