Choosing Multiple Parameters for Support Vector Machines

OLIVIER CHAPELLEVLADIMIR VAPNIKOLIVIER BOUSQUETSAYAN MUKHERJEE

article2002Machine-mediated learning2,407 citations

Proposes a gradient descent framework to automatically tune large numbers of support vector machine hyperparameters and kernel scaling factors by minimizing generalization error bounds, enabling simultaneous kernel optimization and feature selection.

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Support vector machines (SVMs) are widely used for classification and pattern recognition, yet their predictive accuracy depends heavily on selecting optimal model parameters. While standard grid-search techniques work well for tuning one or two settings, they become computationally intractable when dealing with multiple parameters, such as individual feature weights. The article sets out to develop and evaluate an automated gradient descent methodology that efficiently tunes large sets of parameters by directly minimizing theoretical estimates of SVM generalization error.

The researchers formulated an iterative optimization framework that alternates between standard SVM training and adjusting model parameters using the gradient of generalization error bounds, particularly the radius-margin bound and regularized span bounds. They smoothed these theoretical bounds to make them mathematically differentiable and tested the approach across diverse benchmarks. The evaluation included standard benchmark datasets, handwritten digit classification (USPS), high-dimensional cancer gene-expression data, and real-time computer vision tasks like face detection.

The findings show that the proposed method scales successfully to more than one hundred parameters without suffering from overfitting. In standard two-parameter benchmarks, gradient descent matched the accuracy of traditional grid-search cross-validation while requiring roughly 100 times fewer training iterations. Furthermore, using this method to optimize individual input feature scaling factors enabled effective feature selection. In leukemia microarray classification, reducing the feature space from over 7,000 genes to 30 genes achieved zero test classification errors, while in medulloblastoma outcome prediction, selecting 60 genes reduced error counts from 24 down to 15. In face detection, reducing inputs to just 60 principal components maintained high accuracy while eliminating prohibitive computational overhead.

These results demonstrate that model development timelines and computational costs can be dramatically decreased while simultaneously improving model explainability and operational efficiency. By automatically shrinking irrelevant feature weights toward zero, the approach naturally identifies critical variables in high-dimensional domains like genomics and accelerates real-time computer vision systems. Crucially, the analysis reveals that an error bound does not need to predict exact error rates with high numeric accuracy; it only needs to preserve the proper location of the optimal parameter values.

Organizations deploying SVMs should adopt gradient-based minimization of the radius-margin bound as a practical, computationally efficient alternative to exhaustive grid searches and span bounds, which present more local minima. Decision-makers should leverage this framework for automated feature selection before deploying complex models into production environments. However, leaders should note that the mathematical derivations assume smooth kernel differentiability and may encounter local minima. Further research is recommended to establish comprehensive theoretical error bounds for the overall automated procedure across broader non-linear problem domains.

  • Paper: A training algorithm for optimal margin classifiers, B. Boser et al. (1992). Reading this foundational work on optimal margin classifiers provides essential context on the dual-space optimization techniques that support vector machines rely on.
  • Paper: Support-vector networks, Corinna Cortes et al. (1995). Understanding this classic introduction to support-vector networks is necessary before exploring automated hyperparameter tuning for them.
Cover for Choosing Multiple Parameters for Support Vector Machines

Abstract

The problem of automatically tuning multiple parameters for pattern recognition Support Vector Machines (SVMs) is considered. This is done by minimizing some estimates of the generalization error of SVMs using a gradient descent algorithm over the set of parameters. Usual methods for choosing parameters, based on exhaustive search become intractable as soon as the number of parameters exceeds two. Some experimental results assess the feasibility of our approach for a large number of parameters (more than 100) and demonstrate an improvement of generalization performance.

Table of Contents

  • 1. Introduction
  • 2. Support vector learning
  • 3. Estimating the performance of an SVM
  • 3.1. Single validation estimate
  • 3.2. Leave-one-out bounds
  • 4. Smoothing the test error estimates
  • 5. Optimizing the kernel parameters
  • 6. Computing the gradient
  • 6.1. Computing the derivative of the margin
  • 6.2. Computing the derivative of the radius
  • 6.3. Computing the derivative of the hyperplane parameters
  • 6.4. Computing the derivative of the span-rule
  • 7. Experiments
  • 7.1. Optimization details
  • 7.2. Benchmark databases
  • 7.3. Automatic selection of scaling factors
  • 8. Feature selection
  • 8.1. Toy data
  • 8.2. DNA microarray data
  • 8.3. Face detection
  • 9. Conclusion
  • Acknowledgments
  • Notes
  • References

Knowls

  1. Knowl 1 — Alternating Optimization Framework for Support Vector Machine Hyperparameters

    algorithm

    The hyperparameter optimization framework tunes continuous kernel and regularization parameters θRn\boldsymbol{\theta} \in \mathbb{R}^n of a Support Vector Machine (SVM) by alternating standard quadratic programming (QP) training for the dual variables α\boldsymbol{\alpha} with gradient descent updates on θ\boldsymbol{\theta} to minimize a differentiable generalization error bound or estimate T(α0(θ),θ)T(\boldsymbol{\alpha}^0(\boldsymbol{\theta}), \boldsymbol{\theta}). To prevent positivity constraints during optimization (for example, on bandwidth σ\sigma or error penalty CC), logarithmic reparameterizations such as θ=(logC,logσ)\boldsymbol{\theta} = (\log C, \log \sigma) are employed.

    Input: Training dataset Z={(xi,yi)}i=1Z = \{(\mathbf{x}_i, y_i)\}_{i=1}^\ell, initial hyperparameter vector θ0\boldsymbol{\theta}_0, learning rate ε>0\varepsilon > 0, criterion function TT
    Output: Optimized hyperparameters θ\boldsymbol{\theta}^*, optimal SVM dual coefficients α0\boldsymbol{\alpha}^0
    Initialize θθ0\boldsymbol{\theta} \leftarrow \boldsymbol{\theta}_0
    repeat
        Compute optimal dual coefficients α0(θ)\boldsymbol{\alpha}^0(\boldsymbol{\theta}) by solving the standard SVM quadratic program:
        α0(θ)=argmaxα(i=1αi12i,j=1αiαjyiyjKθ(xi,xj))\boldsymbol{\alpha}^0(\boldsymbol{\theta}) = \arg\max_{\boldsymbol{\alpha}} \left( \sum_{i=1}^\ell \alpha_i - \frac{1}{2} \sum_{i,j=1}^\ell \alpha_i \alpha_j y_i y_j K_{\boldsymbol{\theta}}(\mathbf{x}_i, \mathbf{x}_j) \right)
        subject to i=1αiyi=0\sum_{i=1}^\ell \alpha_i y_i = 0 and αi0\alpha_i \ge 0
        
        Evaluate the gradient θT(α0,θ)\nabla_{\boldsymbol{\theta}} T(\boldsymbol{\alpha}^0, \boldsymbol{\theta})
        
        Update parameters via gradient step:
        θθεθT(α0,θ)\boldsymbol{\theta} \leftarrow \boldsymbol{\theta} - \varepsilon \nabla_{\boldsymbol{\theta}} T(\boldsymbol{\alpha}^0, \boldsymbol{\theta})
        (or Newton step θθ(ΔθT)1θT(α0,θ)\boldsymbol{\theta} \leftarrow \boldsymbol{\theta} - (\Delta_{\boldsymbol{\theta}} T)^{-1} \nabla_{\boldsymbol{\theta}} T(\boldsymbol{\alpha}^0, \boldsymbol{\theta}) where (ΔθT)ij=2Tθiθj(\Delta_{\boldsymbol{\theta}} T)_{ij} = \frac{\partial^2 T}{\partial \theta_i \partial \theta_j})
    until stopping criterion on TT is met
    return θ,α0(θ)\boldsymbol{\theta}, \boldsymbol{\alpha}^0(\boldsymbol{\theta})
  2. Knowl 2 — Derivative of Parametric Constrained Quadratic Maxima

    theoretical result

    Let vθRn\mathbf{v}_\theta \in \mathbb{R}^n and PθRn×n\mathbf{P}_\theta \in \mathbb{R}^{n \times n} be a vector and matrix depending smoothly on a scalar parameter θ\theta. Consider the constrained quadratic optimization objective:

    L(θ)=maxxF(xTvθ12xTPθx)L(\theta) = \max_{\mathbf{x} \in \mathcal{F}} \left( \mathbf{x}^T \mathbf{v}_\theta - \frac{1}{2} \mathbf{x}^T \mathbf{P}_\theta \mathbf{x} \right)

    over the convex feasible domain F={xRn:bTx=c,x0}\mathcal{F} = \{\mathbf{x} \in \mathbb{R}^n : \mathbf{b}^T \mathbf{x} = c, \mathbf{x} \ge 0\}. If the maximizer xˉ=argmaxxF(xTvθ12xTPθx)\bar{\mathbf{x}} = \arg\max_{\mathbf{x} \in \mathcal{F}} (\mathbf{x}^T \mathbf{v}_\theta - \frac{1}{2} \mathbf{x}^T \mathbf{P}_\theta \mathbf{x}) is unique, the function L(θ)L(\theta) is differentiable with respect to θ\theta, and its derivative is given by:

    L(θ)θ=xˉTvθθ12xˉTPθθxˉ\frac{\partial L(\theta)}{\partial \theta} = \bar{\mathbf{x}}^T \frac{\partial \mathbf{v}_\theta}{\partial \theta} - \frac{1}{2} \bar{\mathbf{x}}^T \frac{\partial \mathbf{P}_\theta}{\partial \theta} \bar{\mathbf{x}}

    This implies that the objective can be differentiated with respect to θ\theta while treating the optimal vector xˉ\bar{\mathbf{x}} as a constant. The result holds unchanged if either or both the equality constraint bTx=c\mathbf{b}^T \mathbf{x} = c and the non-negativity constraint x0\mathbf{x} \ge 0 are omitted.

  3. Knowl 3 — Gradients of the Radius-Margin Bound with Respect to Kernel Parameters

    theoretical result

    For a hard-margin SVM (or a soft-margin SVM with quadratic error penalization converted to hard-margin via the modified kernel KK+1CI\mathbf{K} \leftarrow \mathbf{K} + \frac{1}{C}\mathbf{I}), the radius-margin generalization error bound is proportional to R2w2=R2/γ2R^2 \|\mathbf{w}\|^2 = R^2 / \gamma^2. Here, RR is the radius of the minimal enclosing sphere in feature space, and γ=1/w\gamma = 1/\|\mathbf{w}\| is the margin.

    The partial derivative of the squared norm of the hyperplane weights w2\|\mathbf{w}\|^2 with respect to a kernel parameter θp\theta_p is:

    w2θp=i,j=1αi0αj0yiyjK(xi,xj)θp\frac{\partial \|\mathbf{w}\|^2}{\partial \theta_p} = -\sum_{i,j=1}^\ell \alpha_i^0 \alpha_j^0 y_i y_j \frac{\partial K(\mathbf{x}_i, \mathbf{x}_j)}{\partial \theta_p}

    where α0\boldsymbol{\alpha}^0 is the vector of optimal dual variables maximizing W(α)W(\boldsymbol{\alpha}).

    The squared radius R2R^2 is computed by maximizing i=1βiK(xi,xi)i,j=1βiβjK(xi,xj)\sum_{i=1}^\ell \beta_i K(\mathbf{x}_i, \mathbf{x}_i) - \sum_{i,j=1}^\ell \beta_i \beta_j K(\mathbf{x}_i, \mathbf{x}_j) subject to i=1βi=1\sum_{i=1}^\ell \beta_i = 1 and βi0\beta_i \ge 0. Its partial derivative with respect to θp\theta_p is:

    R2θp=i=1βi0K(xi,xi)θpi,j=1βi0βj0K(xi,xj)θp\frac{\partial R^2}{\partial \theta_p} = \sum_{i=1}^\ell \beta_i^0 \frac{\partial K(\mathbf{x}_i, \mathbf{x}_i)}{\partial \theta_p} - \sum_{i,j=1}^\ell \beta_i^0 \beta_j^0 \frac{\partial K(\mathbf{x}_i, \mathbf{x}_j)}{\partial \theta_p}

    where β0\boldsymbol{\beta}^0 is the optimal solution to the minimal enclosing sphere quadratic program.

  4. Knowl 4 — Regularized Span of Support Vectors and Its Closed-Form Derivative

    model/method

    The unregularized span of support vectors Sp2=1/(K~SV1)ppS_p^2 = 1/(\tilde{\mathbf{K}}_{SV}^{-1})_{pp} exhibits jump discontinuities whenever the set of support vectors changes during hyperparameter updates. To make the span continuous and differentiable for gradient descent, a regularization penalty is introduced into the span definition for each support vector xp\mathbf{x}_p:

    Sp2=minλ,ipλi=1Φ(xp)ipλiΦ(xi)2+ηip1αi0λi2S_p^2 = \min_{\boldsymbol{\lambda},\, \sum_{i \ne p} \lambda_i = 1} \left\| \Phi(\mathbf{x}_p) - \sum_{i \ne p} \lambda_i \Phi(\mathbf{x}_i) \right\|^2 + \eta \sum_{i \ne p} \frac{1}{\alpha_i^0} \lambda_i^2

    where η>0\eta > 0 is a regularization parameter (typically set to η=0.1\eta = 0.1), Φ(x)\Phi(\mathbf{x}) is the feature map, and αi0\alpha_i^0 are the SVM dual variables.

    In matrix notation, the regularized span for support vector pp is computed in closed form as:

    Sp2=1(K~SV+D)pp1DppS_p^2 = \frac{1}{(\tilde{\mathbf{K}}_{SV} + \mathbf{D})^{-1}_{pp}} - D_{pp}

    where K~SV=(KSV11T0)\tilde{\mathbf{K}}_{SV} = \begin{pmatrix} \mathbf{K}_{SV} & \mathbf{1} \\ \mathbf{1}^T & 0 \end{pmatrix}, KSV\mathbf{K}_{SV} is the kernel matrix on the support vectors, and D\mathbf{D} is a diagonal matrix with diagonal entries Dii=η/αi0D_{ii} = \eta / \alpha_i^0 for inSVi \le n_{SV} and DnSV+1,nSV+1=0D_{n_{SV}+1, n_{SV}+1} = 0.

    The derivative of the regularized span with respect to a kernel parameter θp\theta_p is:

    Sp2θp=Sp4[(K~SV+D)1K~SVθp(K~SV+D)1]pp\frac{\partial S_p^2}{\partial \theta_p} = S_p^4 \left[ (\tilde{\mathbf{K}}_{SV} + \mathbf{D})^{-1} \frac{\partial \tilde{\mathbf{K}}_{SV}}{\partial \theta_p} (\tilde{\mathbf{K}}_{SV} + \mathbf{D})^{-1} \right]_{pp}

    When η0\eta \to 0, this estimate recovers the Opper-Winther bound, and when η\eta \to \infty, it recovers the Jaakkola-Haussler bound.

  5. Knowl 5 — Exact Gradient of Hyperplane Parameters with Respect to Kernel Parameters

    equation

    When non-support vectors are omitted, the active Karush-Kuhn-Tucker (KKT) equality conditions on the margin for an SVM with threshold bb and nn support vectors can be written as the linear system:

    H(α0b)=(10),where H=(KYyyT0)\mathbf{H} \begin{pmatrix} \boldsymbol{\alpha}^0 \\ b \end{pmatrix} = \begin{pmatrix} \mathbf{1} \\ 0 \end{pmatrix}, \quad \text{where } \mathbf{H} = \begin{pmatrix} \mathbf{K}_Y & \mathbf{y} \\ \mathbf{y}^T & 0 \end{pmatrix}

    Here, (KY)ij=yiyjK(xi,xj)(\mathbf{K}_Y)_{ij} = y_i y_j K(\mathbf{x}_i, \mathbf{x}_j), y=(y1,,yn)T\mathbf{y} = (y_1, \dots, y_n)^T, and 1=(1,,1)TRn\mathbf{1} = (1, \dots, 1)^T \in \mathbb{R}^n.

    Differentiating the identity (α0,b)T=H1(1T,0)T(\boldsymbol{\alpha}^0, b)^T = \mathbf{H}^{-1} (\mathbf{1}^T, 0)^T using the matrix inverse derivative M1θp=M1MθpM1\frac{\partial \mathbf{M}^{-1}}{\partial \theta_p} = -\mathbf{M}^{-1} \frac{\partial \mathbf{M}}{\partial \theta_p} \mathbf{M}^{-1} yields:

    (α0,b)Tθp=H1Hθp(α0b)\frac{\partial (\boldsymbol{\alpha}^0, b)^T}{\partial \theta_p} = -\mathbf{H}^{-1} \frac{\partial \mathbf{H}}{\partial \theta_p} \begin{pmatrix} \boldsymbol{\alpha}^0 \\ b \end{pmatrix}

  6. Knowl 6 — Gradient-Based Feature Selection via Kernel Scaling Factors

    algorithm

    Feature selection is conducted by assigning individual scaling factors θi\theta_i to each input feature (or principal component) within the kernel function: Kθ(x,z)=K(θTx,θTz)K_{\boldsymbol{\theta}}(\mathbf{x}, \mathbf{z}) = K(\boldsymbol{\theta}^T \mathbf{x}, \boldsymbol{\theta}^T \mathbf{z}) in input space, or Kθ(x,z)=K(θTΣx,θTΣz)K_{\boldsymbol{\theta}}(\mathbf{x}, \mathbf{z}) = K(\boldsymbol{\theta}^T \boldsymbol{\Sigma} \mathbf{x}, \boldsymbol{\theta}^T \boldsymbol{\Sigma} \mathbf{z}) in principal component space where Σ\boldsymbol{\Sigma} is the principal component projection matrix. Features associated with scaling factors that become sufficiently small during gradient descent are iteratively eliminated.

    Input: Training dataset Z={(xi,yi)}i=1Z = \{(\mathbf{x}_i, y_i)\}_{i=1}^\ell, input dimensionality nn, target number of features mm or pruning threshold, error bound criterion TT
    Output: Reduced feature set and trained SVM model
    Initialize scaling vector θ(1,1,,1)Rn\boldsymbol{\theta} \leftarrow (1, 1, \dots, 1) \in \mathbb{R}^n
    If scaling in principal component space, compute PCA projection matrix Σ\boldsymbol{\Sigma}
    repeat
        Solve the standard SVM quadratic optimization problem using kernel KθK_{\boldsymbol{\theta}}
        repeat
            Update θ\boldsymbol{\theta} using a gradient descent step on T(α0,θ)T(\boldsymbol{\alpha}^0, \boldsymbol{\theta}) with respect to θ\boldsymbol{\theta}
            Re-solve the SVM quadratic optimization problem with updated θ\boldsymbol{\theta}
        until a local minimum of TT is reached
        Discard feature dimensions corresponding to the smallest scaling coefficients θi\theta_i
        Re-initialize or adjust θ\boldsymbol{\theta} on the remaining feature subspace
    until desired number of features or convergence criteria is met
    return selected features and final SVM classifier
  7. Knowl 7 — Smoothed Validation Error via SVM Posterior Class Probabilities

    model/method

    To compute gradients of validation error when using a held-out validation set {(xi,yi)}i=1nv\{(\mathbf{x}_i', y_i')\}_{i=1}^{n_v}, the non-differentiable step 0-1 loss is smoothed by estimating posterior class probabilities using Platt's sigmoid model on the continuous SVM output f(x)f(\mathbf{x}):

    P~A,B(Y=1X=x)=11+exp(Af(x)+B)\tilde{P}_{A,B}(Y=1 \mid X=\mathbf{x}) = \frac{1}{1 + \exp(A f(\mathbf{x}) + B)}

    The parameters AA^* and BB^* are fitted via second-order gradient descent by minimizing the Kullback-Leibler divergence on the validation set:

    (A,B)=argmaxA,Bi=1nv[1+yi2logP~A,B(xi)+1yi2log(1P~A,B(xi))](A^*, B^*) = \arg\max_{A,B} \sum_{i=1}^{n_v} \left[ \frac{1 + y_i'}{2} \log \tilde{P}_{A,B}(\mathbf{x}_i') + \frac{1 - y_i'}{2} \log(1 - \tilde{P}_{A,B}(\mathbf{x}_i')) \right]

    The smoothed empirical generalization error TT to be minimized with respect to kernel parameters is then evaluated as:

    T=i=1nvmin(P~A,B(xi),1P~A,B(xi))T = \sum_{i=1}^{n_v} \min\left( \tilde{P}_{A^*, B^*}(\mathbf{x}_i'),\, 1 - \tilde{P}_{A^*, B^*}(\mathbf{x}_i') \right)

  8. Knowl 8 — Generalization Error and Computational Cost of Bound Minimization vs Cross-Validation

    data/table

    Gradient descent optimization of the radius-margin bound (R2/γ2R^2/\gamma^2) and the span bound was compared against standard 5-fold cross-validation on 5 benchmark datasets for selecting the soft-margin constant CC and RBF kernel width σ\sigma. Across all datasets, bound minimization achieved test error rates matching 5-fold cross-validation while requiring approximately 100 times fewer SVM training iterations (3 to 14.2 training runs per split for R2/γ2R^2/\gamma^2 and 3.4 to 11.6 for the span bound, compared to 500 training runs for 5-fold CV over a 10×1010 \times 10 grid).

    Test Error (%) Average SVM Trainings
    Dataset Cross-validation R2/γ2R^2/\gamma^2 Span-bound Cross-validation R2/γ2R^2/\gamma^2 Span-bound
    Breast cancer 26.04±4.7426.04 \pm 4.74 26.84±4.7126.84 \pm 4.71 25.59±4.1825.59 \pm 4.18 500 14.2 7.0
    Diabetes 23.53±1.7323.53 \pm 1.73 23.25±1.7023.25 \pm 1.70 23.19±1.6723.19 \pm 1.67 500 12.2 9.8
    Heart 15.95±3.2615.95 \pm 3.26 15.92±3.1815.92 \pm 3.18 16.13±3.1116.13 \pm 3.11 500 9.0 6.2
    Thyroid 4.80±2.194.80 \pm 2.19 4.62±2.034.62 \pm 2.03 4.56±1.974.56 \pm 1.97 500 3.0 11.6
    Titanic 22.42±1.0222.42 \pm 1.02 22.88±1.2322.88 \pm 1.23 22.50±0.8822.50 \pm 0.88 500 6.8 3.4
  9. Knowl 9 — Feature Selection on Synthetic Linear and Non-Linear Benchmarks

    empirical result

    The gradient descent feature selection method based on R2/γ2R^2/\gamma^2 and regularized span bounds was evaluated on synthetic datasets containing irrelevant and redundant dimensions, keeping the top two selected features:

    1. Linear problem (202 dimensions total, 6 relevant): Dimensions x1,x2,x3x_1, x_2, x_3 were drawn as xi=yN(i,1)x_i = y \mathcal{N}(i, 1) and x4,x5,x6x_4, x_5, x_6 as N(0,1)\mathcal{N}(0, 1) with probability 0.7 (and vice versa with probability 0.3); remaining features x7,,x202N(0,20)x_7, \dots, x_{202} \sim \mathcal{N}(0, 20). Using a linear kernel, the bound minimization selection method strongly outperformed standard SVMs and filter methods (Pearson correlation, Fisher score, Kolmogorov-Smirnov).

    2. Non-linear problem (52 dimensions total, 2 relevant): y=1y = -1 examples were drawn from equal-probability mixtures of N(μ1,I)\mathcal{N}(\boldsymbol{\mu}_1, \mathbf{I}) and N(μ2,I)\mathcal{N}(\boldsymbol{\mu}_2, \mathbf{I}) with μ1=(3/4,3)\boldsymbol{\mu}_1 = (-3/4, -3) and μ2=(3/4,3)\boldsymbol{\mu}_2 = (3/4, 3); y=1y = 1 examples were drawn from μ1=(3,3)\boldsymbol{\mu}_1 = (3, -3) and μ2=(3,3)\boldsymbol{\mu}_2 = (-3, 3). Noise features x3,,x52N(0,20)x_3, \dots, x_{52} \sim \mathcal{N}(0, 20). Using a second-order polynomial kernel, bound minimization successfully isolated the two true informative dimensions, while standard SVMs and filter methods (except Kolmogorov-Smirnov) suffered severe degradation.

  10. Knowl 10 — Feature Selection on High-Dimensional DNA Microarray and Face Detection Applications

    empirical result

    Feature selection using gradient descent on the R2/γ2R^2/\gamma^2 and span bounds was evaluated on high-dimensional real-world tasks:

    1. Leukemia Classification (Myeloid vs. Lymphoblastic, 7129 genes, 38 train / 34 test): Standard linear SVM achieved 1 test error. Gradient descent on R2/γ2R^2/\gamma^2 achieved 0 test errors using 30 selected genes (and 1 test error with just 1 gene), whereas Fisher criterion feature selection resulted in 1 test error for both 1 and 30 genes.

    2. Lymphoblastic Cell Subtyping (B vs. T cells, 7129 genes): Standard linear SVM made 1 error. Both R2/γ2R^2/\gamma^2 and span bound minimization achieved 0 errors using 5 selected genes, compared to 2 errors for the Fisher criterion using 5 genes.

    3. Medulloblastoma Treatment Outcome (7129 genes, 60 examples): Evaluated via leave-one-out error. Standard Gaussian SVM made 24 errors, whereas selecting 60 genes via R2/γ2R^2/\gamma^2 gradient descent reduced the error to 15.

    4. Face Detection (CMU dataset, 479 faces, 57,000,000 non-face patterns): Selecting features via scaling factors in PCA space reduced the input dimension from 283 gray features to 60 principal components without loss of classification performance on the ROC curve, enabling real-time scanning.

Coverage note — None was omitted; all key theoretical derivations, bounds, algorithms, smoothing methods, and experimental datasets from the paper are represented.

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Citation

MLA
Chapelle, O., et al. “Choosing Multiple Parameters for Support Vector Machines”. Machine Learning, vol. 46, nos. 1-3, 2002, pp. 131–59, https://doi.org/10.1023/A:1012450327387.
APA
Chapelle, O., Vapnik, V., Bousquet, O., & Mukherjee, S. (2002). Choosing Multiple Parameters for Support Vector Machines. Machine Learning, 46(1-3), 131–159. https://doi.org/10.1023/A:1012450327387
Chicago
Chapelle, O., V. Vapnik, O. Bousquet, and S. Mukherjee. 2002. “Choosing Multiple Parameters for Support Vector Machines”. Machine Learning 46 (1-3): 131–59. https://doi.org/10.1023/A:1012450327387.
Harvard
Chapelle, O. et al. (2002) “Choosing Multiple Parameters for Support Vector Machines”, Machine Learning, 46(1-3), pp. 131–159. Available at: https://doi.org/10.1023/A:1012450327387.
Vancouver
1. Chapelle O, Vapnik V, Bousquet O, Mukherjee S (2002) Choosing Multiple Parameters for Support Vector Machines. Machine Learning 46:131–159

BibTeX

@article{Chapelle_2002, title={Choosing Multiple Parameters for Support Vector Machines}, volume={46}, ISSN={1573-0565}, url={http://dx.doi.org/10.1023/A:1012450327387}, DOI={10.1023/a:1012450327387}, number={1-3}, journal={Machine Learning}, publisher={Springer Science and Business Media LLC}, author={Chapelle, Olivier and Vapnik, Vladimir and Bousquet, Olivier and Mukherjee, Sayan}, year={2002}, month=Jan, pages={131–159} }
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