Evolution-Inspired Sample Competition for Deep Neural Network Optimization
Authors: Ying Zheng, Yiyi Zhang, Yi Wang, Lap-Pui Chau
Organizations: Department of Electrical and Electronic Engineering, The Hong Kong Polytechnic University, Hong Kong, China. · Department of Computer Science and Engineering, The Chinese University of Hong Kong, Hong Kong, China.
Conventional deep network training generally optimizes all samples under a largely uniform learning paradigm, without explicitly modeling the heterogeneous competition among them. Such an oversimplified treatment can lead to several well-known issues, including bias under class imbalance, insufficient learning of hard samples, and the erroneous reinforcement of noisy samples. In this work, we present Natural Selection (NS), a novel evolution-inspired optimization method that explicitly incorporates competitive interactions into deep network training. Unlike conventional sample reweighting strategies that rely mainly on predefined heuristics or static criteria, NS estimates the competitive status of each sample in a group-wise context and uses it to adaptively regulate its training contribution. Specifically, NS first assembles multiple samples into a composite image and rescales it to the original input size for model inference. Based on the resulting predictions, a natural selection score is computed for each sample to characterize its relative competitive variation within the constructed group. These scores are then used to dynamically reweight the sample-wise loss, thereby introducing an explicit competition-driven mechanism into the optimization process. In this way, NS provides a simple yet effective means of moving beyond uniform sample treatment and enables more adaptive and balanced model optimization. Extensive experiments on 12 public datasets across four image classification tasks demonstrate the effectiveness of the proposed method. Moreover, NS is compatible with diverse network architectures and does not depend on task-specific assumptions, indicating its strong generality and practical potential. The code will be made publicly available.
Figures & tables
Fig. 1: (a) Natural selection in ecosystem evolution. (b) Illustration of the natural selection process in training samples. After performing image stitching and scale normalization, the resulting stitched image is fed into the classifier to obtain the softmax probability distribution. The predicted probability associated with each sample’s category is then extracted, and the NS score is subsequently computed through normalization.
p(g)=softmax(fθ(S′(g))).
Algorithm 1 Natural Selection Score Computation
Fig. 2: The distribution curves of sample weights under different settings. Under the NS-WS (green dashed line) and NS-LF (purple dashed line) strategies, samples with higher-weight values are reinforced during training, while those in lower-weight regions are suppressed. This enables differentiated optimization for samples with varying competitive characteristics.
Method
Basic
w/ NS
LF-2
WS-2
LF-4
WS-4
ResNet-18 [ 53 ]
68.4
68.4
68.6
68.4
68.9 ( ↑ 0.5 )
Swin-T [ 57 ]
75.2
75.4
75.5
75.2
75.7 ( ↑ 0.5 )
VMamba-T [ 58 ]
76.7
76.9
76.9
76.8
77.1 ( ↑ 0.4 )
TABLE I: Evaluation of NS on ImageNet-1K . “WS” denotes boosting the winner, while “LF” means enhancing the loser. “2/4” indicates grouping two or four samples for competition.
Method
CIFAR-10
CIFAR-100
Basic
w/ NS-WS
Basic
w/ NS-WS
AlexNet [ 51 ]
77.4
78.6 ( ↑ 1.2 )
43.8
46.0 ( ↑ 2.2 )
VGG-19 [ 52 ]
93.4
93.8 ( ↑ 0.4 )
71.7
72.6 ( ↑ 0.9 )
ResNet-110 [ 53 ]
92.8
93.9 ( ↑ 1.1 )
70.3
72.1 ( ↑ 1.8 )
ResNeXt-29 [ 54 ]
95.9
96.2 ( ↑ 0.3 )
81.4
82.3 ( ↑ 0.9 )
TABLE II: Evaluation of NS-WS on CIFAR-10/100 with different networks.
Method
Twitter I
Twitter II
Flickr
Instagram
FI
EmoSet
Basic
w/ NS-LF
Basic
w/ NS-LF
Basic
w/ NS-LF
Basic
w/ NS-LF
Basic
w/ NS-LF
Basic
w/ NS-LF
AlexNet [ 51 ]
73.8
75.2
68.5
71.0
83.2
83.8
80.6
81.2
56.4
57.9
67.6
69.2
VGG-16 [ 52 ]
75.3
78.1
74.3
74.9
84.4
84.6
82.5
83.1
59.7
61.4
72.2
73.9
ResNet-50 [ 53 ]
81.3
82.9
71.0
74.3
85.7
86.4
84.6
85.2
65.8
67.2
75.8
76.3
DenseNet-121 [ 55 ]
78.9
79.4
72.8
74.0
85.1
85.6
84.0
85.0
63.2
64.4
74.9
75.2
ViT-B/16 [ 56 ]
74.5
76.4
72.1
72.2
86.2
86.4
84.5
85.3
65.6
67.4
77.3
77.7
TABLE III: Comparison of basic and NS-enhanced models on six emotion recognition datasets.
Method
Ar → Cl
Ar → Pr
Ar → Rw
Cl → Ar
Cl → Pr
Cl → Rw
Pr → Ar
Pr → Cl
Pr → Rw
Rw → Ar
Rw → Cl
Rw → Pr
Avg.
Baseline
58.0
78.8
81.9
69.4
79.7
78.7
68.2
55.0
81.9
73.8
58.7
83.8
72.3
Focal Loss [ 5 ]
57.9
78.8
82.0
69.2
79.8
78.6
68.3
55.4
81.8
73.7
59.9
83.7
72.4
GCE [ 62 ]
57.5
77.7
80.9
68.8
76.5
77.3
66.9
54.5
80.9
73.8
58.7
84.1
71.5
LS [ 63 ]
58.0
78.7
82.0
69.3
79.7
78.6
68.3
55.3
81.9
73.8
59.7
83.9
72.4
NLNL [ 64 ]
56.4
77.5
80.1
67.4
75.6
76.3
65.5
54.8
80.5
73.4
59.0
83.5
70.8
SCE [ 65 ]
54.5
78.3
80.6
63.8
76.7
76.2
65.3
50.4
80.6
70.5
53.7
82.8
69.4
TABLE IV: Comparison of different methods on the Office-Home benchmark.
Method
CIFAR-LT-10
CIFAR-LT-100
200
100
50
10
200
100
50
10
Baseline
64.0
69.5
72.7
86.7
33.6
38.4
42.1
53.8
Focal Loss [ 5 ]
60.2
69.5
73.4
86.9
33.6
37.6
43.6
55.4
GCE [ 62 ]
46.3
60.3
63.8
86.2
18.6
21.8
25.3
36.8
LS [ 63 ]
62.5
70.3
74.8
86.8
32.9
37.8
42.9
56.0
NLNL [ 64 ]
33.0
35.1
39.0
52.6
1.9
1.6
1.6
2.2
TABLE V: Performance comparison on the CIFAR-LT-10/100 datasets.
Group
1 × 2
2 × 2
2 × 4
4 × 2
4 × 4
Acc (%)
72.0
72.1
71.7
71.4
71.7
TABLE VI: Evaluation of five different grouped stitching configurations.
σ
0.0
0.1
0.5
0.8
1.0
1.5
1.8
Acc (%)
67.5
70.9
71.3
72.1
71.7
71.5
71.4
TABLE VII: Performance with different values of σ .
ρ
0.0
0.1
0.5
0.8
1.0
1.5
1.8
Acc (%)
70.3
71.3
71.6
71.8
72.1
71.9
71.8
TABLE VIII: Performance with different values of ρ .
Dataset
Mean ± Std
Dataset
Mean ± Std
ImageNet-1K
73.9 ± 0.05
Instagram
83.7 ± 0.21
CIFAR-10
91.8 ± 0.08
FI
64.2 ± 0.26
CIFAR-100
70.9 ± 0.22
EmoSet
75.1 ± 0.12
Twitter I
77.0 ± 0.45
Office-Home
73.0 ± 0.19
Twitter II
73.3 ± 0.34
CIFAR-LT-10
74.9 ± 0.43
Flickr
85.5 ± 0.11
CIFAR-LT-100
43.9 ± 0.18
TABLE IX: Mean and standard deviation of the performance on the 12 public datasets.
Dataset
ResNet-18
w/ NS-WS
ImageNet-Hard
9.9
10.2
TABLE X: Results on the ImageNet-Hard dataset.
Fig. 3: Visualization of NS score distributions by category on the CIFAR-10 and FI datasets. Red points denote training samples, and the blue solid line within each box indicates the median NS score of all samples in that class.
Dataset
TextCNN
w/ NS-LF
BERT-base
w/ NS-LF
IMDB
75.6
76.6
91.8
92.2
AG News
90.3
91.0
94.4
94.7
TABLE XI: Results on the IMDB and AG News datasets.
Method
CIFAR-10
CIFAR-100
Memory
Time
Memory
Time
(MB)
(s)
(MB)
(s)
ResNet-110
1,564
23.81
1,564
23.93
w/ NS
1,588 ( ↑ 1.5% )
26.24 ( ↑ 10.2% )
1,588 ( ↑ 1.5% )
26.97 ( ↑ 12.7% )
TABLE XII: Computational overhead of NS in terms of GPU memory usage and per-epoch training time.
Operation
CIFAR-10
CIFAR-100
Stitching & scaling
0.14 s
0.14 s
Model inference
2.31 s
2.87 s
TABLE XIII: Per-step runtime breakdown of NS.
Fig. 4: Correlation analysis on the CIFAR-LT-10/100 and Office-Home datasets. Blue points represent the individual categories, while the red line depicts the fitted linear regression.
The optimization of over-parameterized deep neural networks represents a large-scale, high-dimensional, and strongly non-convex decision problem that challenges existing optimization frameworks. Current evolutionary and gradient-based pruning methods often struggle to scale to such dimensionalities, as they rely on flat search spaces, scalarized objectives, or repeated retraining, leading to premature convergence and prohibitive computational cost. This paper introduces a hierarchical importance-guided evolutionary framework that reformulates convolutional network pruning as a tractable large-scale multi-objective optimization problem. In the first phase, a continuous evolutionary search performs coarse exploration of weight-wise pruning thresholds to shrink the search space and identify promising regions of the Pareto set. The second phase applies a fine-grained binary evolutionary optimization constrained to the surviving weights, where importance-aware sampling and adaptive variation operators refine local search in the sparse region of the Pareto set. This hierarchical design combines global exploration and localized exploitation to achieve a well-distributed Pareto set of networks balancing compactness and accuracy. Empirical results on CIFAR-10 and CIFAR-100 using ResNet-56 and ResNet-110 confirm the method's effectiveness compared to existing evolutionary approaches: pruning achieves up to 51.9% and 38.9% parameter reductions with almost no accuracy loss compared to state-of-the-art evolutionary DNN pruning methods. The proposed method contributes a scalable evolutionary approach for solving very-large-scale multi-objective optimization problems, offering a general paradigm extendable to other domains where the decision space is exponentially large, objective functions are conflicting, and efficient trade-off discovery is essential.
Zak Khan, Azam Asilian Bidgoli
Department of Computer Science and Physics, Wilfrid Laurier University, Waterloo, N2L 3C5, Ontario, Canada
Dynamic Data selection aims to accelerate training by prioritizing informative samples during online training. However, existing methods typically rely on task-specific handcrafted metrics or static/snapshot-based criteria to estimate sample importance, limiting scalability across learning paradigms and making it difficult to capture the evolving utility of data throughout training. To address this challenge, we propose Data Agent, an end-to-end dynamic data selection framework that formulates data selection as a training-aware sequential decision-making problem. The agent learns a sample-wise selection policy that co-evolves with model optimization, guided by a composite reward that integrates loss-based difficulty and confidence-based uncertainty signals. The reward signals capture complementary objectives of optimization impact and information gain, together with a tuning-free adaptive weighting mechanism that balances these signals over training. Extensive experiments across a wide range of datasets and architectures demonstrate that Data Agent consistently accelerates training while preserving or improving performance, e.g., reducing costs by over 50% on ImageNet-1k and MMLU with lossless performance. Moreover, its dataset-agnostic formulation and modular reward make it plug-and-play across tasks and scenarios, e.g., robustness to noisy datasets, highlighting its potential in real-world scenarios. Code is available at https://github.com/Jackbrocp/Data-Agent.
Suorong Yang, Fangjian Su, Hai Gan +5
National University of Singapore · Nanjing University · Nanyang Technological University
Deep neural networks are typically trained by uniformly sampling large datasets across epochs, despite evidence that not all samples contribute equally throughout learning. Recent work shows that progressively reducing the amount of training data can improve efficiency and generalization, but existing methods rely on fixed schedules that do not adapt during training. In this work, we propose Adaptive Data Dropout, a simple framework that dynamically adjusts the subset of training data based on performance feedback. Inspired by self-regulated learning, our approach treats data selection as an adaptive process, increasing or decreasing data exposure in response to changes in training accuracy. We introduce a lightweight stochastic update mechanism that modulates the dropout schedule online, allowing the model to balance exploration and consolidation over time. Experiments on standard image classification benchmarks show that our method reduces effective training steps while maintaining competitive accuracy compared to static data dropout strategies. These results highlight adaptive data selection as a promising direction for efficient and robust training. Code will be released.
Amar Gahir, Varshil Patel, Shreyank N Gowda
School of Computer Science, University of Nottingham, Nottingham, United Kingdom