Rademacher and Gaussian Complexities: Risk Bounds and Structural Results

P. BartlettS. Mendelson

article2002JMLR3,331 citations

Establishes data-dependent generalization bounds using Rademacher and Gaussian complexities alongside structural composition rules that yield practical error guarantees for neural networks, kernel methods, and decision trees.

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The paper develops data-dependent measures of function-class complexity, specifically Rademacher and Gaussian complexities, to derive tighter risk bounds for learning algorithms and to relate the complexity of composite classes to that of simpler basis classes. Traditional bounds that rely on fixed penalties such as VC-dimension often fail to adapt to the training sample and therefore produce overly conservative model-selection rules. The authors address this limitation by proving general error bounds expressed directly in terms of empirical Rademacher or Gaussian averages and by establishing structural inequalities that allow these averages to be computed or bounded for practical model families.

The central results establish that, with high probability, the true risk of any function is at most its empirical risk plus a term proportional to the Rademacher complexity of a suitably transformed class, plus a small additive deviation of order 1/√n. The same bounds hold when the Rademacher term is replaced by its Gaussian counterpart, which differs from it by at most a logarithmic factor. Additional lemmas show that these complexities are comparable to the maximum discrepancy of the class and that they satisfy natural monotonicity, scaling, and Lipschitz-composition properties. For classes formed by convex combinations, Boolean operations, or Lipschitz maps of simpler classes, the complexity of the composite is controlled by the sum of the complexities of the components, scaled by constants that depend only on the Lipschitz constants or the number of summands.

These abstract bounds translate into concrete improvements for concrete models. For decision trees the resulting penalty can be substantially smaller than a uniform VC-style term whenever many leaves receive little empirical mass. For two-layer neural networks with ℓ1 weight constraints the Gaussian complexity scales with the square root of the maximum pairwise distance among input coordinates, again data-dependent. For kernel expansions the same machinery yields a margin-based bound whose complexity term is proportional to the trace of the empirical kernel matrix. In each case the derived penalty decreases at rate 1/√n or faster and never exceeds the order of classical combinatorial-dimension bounds.

Because the penalties adapt to the observed sample, they support more reliable complexity-regularization procedures for model selection. The structural results further reduce the computational burden by allowing the optimization that defines the complexity to be performed only over the simpler basis classes rather than over the full composite class. The main limitation is that exact evaluation still requires solving a non-convex optimization problem whose difficulty grows with model size; practical use therefore depends on efficient approximation schemes or on further tightening of the structural inequalities.

  • Paper: A training algorithm for optimal margin classifiers, B. Boser et al. (1992). Reading the foundational optimal margin classifier paper provides the essential structural background on support vector machines and margin maximization that the source paper analyzes via Rademacher complexities.
Cover for Rademacher and Gaussian Complexities: Risk Bounds and Structural Results

Abstract

We investigate the use of certain data-dependent estimates of the complexity of a function class, called Rademacher and Gaussian complexities. In a decision theoretic setting, we prove general risk bounds in terms of these complexities. We consider function classes that can be expressed as combinations of functions from basis classes and show how the Rademacher and Gaussian complexities of such a function class can be bounded in terms of the complexity of the basis classes. We give examples of the application of these techniques in finding data-dependent risk bounds for decision trees, neural networks and support vector machines.

Table of Contents

  • 1. Introduction
  • 2. Risk Bounds
  • 3. Estimating the Rademacher and Gaussian Complexities of Function Classes
  • 3.1 Simple Structural Results
  • 3.2 Lipschitz Functions on Rk\mathbb{R}^k
  • 3.3 Boolean Combinations of Functions
  • 4. Examples
  • 4.1 Decision Trees
  • 4.2 Neural Networks
  • 4.3 Kernel Methods
  • Acknowledgments
  • Appendix A. Proof of Lemma 3
  • Appendix B. Proof of Theorem 5
  • References

Knowls

  1. Knowl 1 — General Decision-Theoretic Risk Bound via Rademacher Complexity

    theoretical result

    Let X\mathcal{X} be an input space, Y\mathcal{Y} an output space, and A\mathcal{A} an action space. Let PP be a probability measure on X×Y\mathcal{X} \times \mathcal{Y}, and let (X1,Y1),,(Xn,Yn)(X_1, Y_1), \dots, (X_n, Y_n) be an independent sample drawn according to PP. Let L:Y×A[0,1]\mathcal{L}: \mathcal{Y} \times \mathcal{A} \to [0, 1] be a loss function, and let ϕ:Y×A[0,1]\phi: \mathcal{Y} \times \mathcal{A} \to [0, 1] be a dominating cost function satisfying ϕ(y,a)L(y,a)\phi(y, a) \ge \mathcal{L}(y, a) for all yYy \in \mathcal{Y} and aAa \in \mathcal{A}.

    For a class FF of functions mapping from X\mathcal{X} to A\mathcal{A}, define the centered composite function class ϕ~F={(x,y)ϕ(y,f(x))ϕ(y,0):fF}.\tilde{\phi} \circ F = \{(x, y) \mapsto \phi(y, f(x)) - \phi(y, 0) : f \in F\}.

    The expected Rademacher complexity Rn(ϕ~F)R_n(\tilde{\phi} \circ F) is defined as Rn(ϕ~F)=E[supfF2ni=1nσi(ϕ(Yi,f(Xi))ϕ(Yi,0))],R_n(\tilde{\phi} \circ F) = \mathbb{E}\left[ \sup_{f \in F} \left| \frac{2}{n} \sum_{i=1}^n \sigma_i \big(\phi(Y_i, f(X_i)) - \phi(Y_i, 0)\big) \right| \right], where σ1,,σn\sigma_1, \dots, \sigma_n are independent Rademacher random variables uniformly distributed on {±1}\{\pm 1\}.

    Then, for any integer n1n \ge 1 and any confidence parameter δ(0,1)\delta \in (0, 1), with probability at least 1δ1 - \delta over samples of length nn, every fFf \in F satisfies E[L(Y,f(X))]1ni=1nϕ(Yi,f(Xi))+Rn(ϕ~F)+8ln(2/δ)n.\mathbb{E}[\mathcal{L}(Y, f(X))] \le \frac{1}{n} \sum_{i=1}^n \phi(Y_i, f(X_i)) + R_n(\tilde{\phi} \circ F) + \sqrt{\frac{8 \ln(2/\delta)}{n}}.

  2. Knowl 2 — Rademacher Complexity, Gaussian Complexity, and Maximum Discrepancy

    definition

    Let μ\mu be a probability distribution on a domain X\mathcal{X}, and let X1,,XnX_1, \dots, X_n be independent samples drawn according to μ\mu. Let FF be a class of real-valued functions mapping from X\mathcal{X} to R\mathbb{R}.

    1. Maximum Discrepancy: The empirical maximum discrepancy is the random variable D^n(F)=supfF(2ni=1n/2f(Xi)2ni=n/2+1nf(Xi)),\hat{D}_n(F) = \sup_{f \in F} \left( \frac{2}{n} \sum_{i=1}^{n/2} f(X_i) - \frac{2}{n} \sum_{i=n/2+1}^n f(X_i) \right), and the expected maximum discrepancy is Dn(F)=E[D^n(F)]D_n(F) = \mathbb{E}[\hat{D}_n(F)].

    2. Rademacher Complexity: Let σ1,,σn\sigma_1, \dots, \sigma_n be independent uniform {±1}\{\pm 1\}-valued random variables. The empirical Rademacher complexity conditioned on the sample is R^n(F)=Eσ[supfF2ni=1nσif(Xi)  |  X1,,Xn],\hat{R}_n(F) = \mathbb{E}_\sigma \left[ \sup_{f \in F} \left| \frac{2}{n} \sum_{i=1}^n \sigma_i f(X_i) \right| \;\middle|\; X_1, \dots, X_n \right], and the expected Rademacher complexity is Rn(F)=E[R^n(F)]R_n(F) = \mathbb{E}[\hat{R}_n(F)].

    3. Gaussian Complexity: Let g1,,gng_1, \dots, g_n be independent standard Gaussian N(0,1)\mathcal{N}(0, 1) random variables. The empirical Gaussian complexity conditioned on the sample is G^n(F)=Eg[supfF2ni=1ngif(Xi)  |  X1,,Xn],\hat{G}_n(F) = \mathbb{E}_g \left[ \sup_{f \in F} \left| \frac{2}{n} \sum_{i=1}^n g_i f(X_i) \right| \;\middle|\; X_1, \dots, X_n \right], and the expected Gaussian complexity is Gn(F)=E[G^n(F)].G_n(F) = \mathbb{E}[\hat{G}_n(F)]. $

  3. Knowl 3 — Structural Calculus Properties of Rademacher Complexity

    theoretical result

    Let F,F1,,FkF, F_1, \dots, F_k, and HH be classes of real-valued functions mapping from a domain X\mathcal{X} to R\mathbb{R}. The expected Rademacher complexity RnR_n satisfies the following structural properties:

    1. Monotonicity: If FHF \subseteq H, then Rn(F)Rn(H)R_n(F) \le R_n(H).

    2. Convex and Absolute Convex Hulls: Rn(F)=Rn(conv(F))=Rn(absconv(F))R_n(F) = R_n(\mathrm{conv}(F)) = R_n(\mathrm{absconv}(F)), where conv(F)\mathrm{conv}(F) is the class of convex combinations of functions in FF, and absconv(F)=conv(FF)\mathrm{absconv}(F) = \mathrm{conv}(F \cup -F).

    3. Homogeneity: For every cRc \in \mathbb{R}, Rn(cF)=cRn(F)R_n(c F) = |c| R_n(F), where cF={cf:fF}c F = \{cf : f \in F\}.

    4. Lipschitz Composition (Contraction): If ϕ:RR\phi: \mathbb{R} \to \mathbb{R} is Lipschitz continuous with constant LϕL_\phi and satisfies ϕ(0)=0\phi(0) = 0, then Rn(ϕF)2LϕRn(F)R_n(\phi \circ F) \le 2 L_\phi R_n(F), where ϕF={ϕf:fF}\phi \circ F = \{\phi \circ f : f \in F\}.

    5. Translation: For any uniformly bounded function h:XRh: \mathcal{X} \to \mathbb{R}, Rn(F+h)Rn(F)+hnR_n(F + h) \le R_n(F) + \frac{\|h\|_\infty}{\sqrt{n}}.

    6. Power Loss Classes: For 1q<1 \le q < \infty and uniformly bounded hh, let LF,h,q={fhq:fF}\mathcal{L}_{F, h, q} = \{ |f - h|^q : f \in F \}. If fh1\|f - h\|_\infty \le 1 for all fFf \in F, then Rn(LF,h,q)2q(Rn(F)+hn).R_n(\mathcal{L}_{F, h, q}) \le 2q \left( R_n(F) + \frac{\|h\|_\infty}{\sqrt{n}} \right).

    7. Direct Sums: Rn(i=1kFi)i=1kRn(Fi)R_n\left(\sum_{i=1}^k F_i\right) \le \sum_{i=1}^k R_n(F_i), and this inequality is tight.

    Properties 1--3 hold identically for expected Gaussian complexity GnG_n, while properties 4--7 hold for GnG_n with an additional multiplicative factor of O(lnn)O(\ln n).

  4. Knowl 4 — Gaussian Complexity of Vector-Valued Lipschitz Compositions

    theoretical result

    Let A=Rm\mathcal{A} = \mathbb{R}^m, and let FF be a class of vector-valued functions mapping from an input space X\mathcal{X} to A\mathcal{A} such that FF1FmF \subseteq F_1 \oplus \dots \oplus F_m for real-valued function classes F1,,FmF_1, \dots, F_m on X\mathcal{X}.

    Assume that ϕ:Y×AR\phi: \mathcal{Y} \times \mathcal{A} \to \mathbb{R} is such that for all yYy \in \mathcal{Y}, ϕ(y,)\phi(y, \cdot) is Lipschitz continuous with constant LL with respect to the Euclidean distance on A\mathcal{A}, passes through the origin (ϕ(y,0)=0\phi(y, 0) = 0), and is uniformly bounded. For fFf \in F, define ϕf\phi \circ f as (x,y)ϕ(y,f(x))(x, y) \mapsto \phi(y, f(x)).

    Then, for every integer nn and every sample (X1,Y1),,(Xn,Yn)(X_1, Y_1), \dots, (X_n, Y_n), the empirical Gaussian averages satisfy G^n(ϕF)2Li=1mG^n(Fi).\hat{G}_n(\phi \circ F) \le 2L \sum_{i=1}^m \hat{G}_n(F_i).

    Consequently, for any loss function L:Y×A[0,1]\mathcal{L}: \mathcal{Y} \times \mathcal{A} \to [0, 1] dominated by a cost function ϕ:Y×A[0,1]\phi: \mathcal{Y} \times \mathcal{A} \to [0, 1], with probability at least 1δ1 - \delta over an independent sample of size nn, every fFf \in F satisfies E[L(Y,f(X))]1ni=1nϕ(Yi,f(Xi))+cLj=1mGn(Fj)+8ln(2/δ)n,\mathbb{E}[\mathcal{L}(Y, f(X))] \le \frac{1}{n} \sum_{i=1}^n \phi(Y_i, f(X_i)) + c L \sum_{j=1}^m G_n(F_j) + \sqrt{\frac{8 \ln(2/\delta)}{n}}, where cc is an absolute constant.

  5. Knowl 5 — Single-Sample Concentration and Estimation of Rademacher Complexity

    theoretical result

    Let FF be a class of functions mapping from X\mathcal{X} to [1,1][-1, 1]. For an independent sample X1,,XnX_1, \dots, X_n drawn from a probability distribution on X\mathcal{X} and independent uniform {±1}\{\pm 1\}-valued Rademacher random variables σ1,,σn\sigma_1, \dots, \sigma_n, the expected Rademacher complexity Rn(F)R_n(F) concentrates sharply around both the empirical Rademacher complexity R^n(F)\hat{R}_n(F) and any single realization of the Rademacher variables.

    For any ϵ>0\epsilon > 0 and any integer n1n \ge 1: P(Rn(F)2nsupfFi=1nσif(Xi)ϵ)2exp(ϵ2n8),\mathbb{P}\left( \left| R_n(F) - \frac{2}{n} \sup_{f \in F} \left| \sum_{i=1}^n \sigma_i f(X_i) \right| \right| \ge \epsilon \right) \le 2 \exp\left( -\frac{\epsilon^2 n}{8} \right), and P(Rn(F)R^n(F)ϵ)2exp(ϵ2n8).\mathbb{P}\left( \left| R_n(F) - \hat{R}_n(F) \right| \ge \epsilon \right) \le 2 \exp\left( -\frac{\epsilon^2 n}{8} \right).

    This establishes that data-dependent complexity penalties can be estimated from a single training sample and a single realization of random signs without requiring prior knowledge of the underlying data distribution.

  6. Knowl 6 — Rademacher Complexity and Margin Risk Bounds for Kernel Methods

    theoretical result

    Let X\mathcal{X} be a compact space and let k:X×XRk: \mathcal{X} \times \mathcal{X} \to \mathbb{R} be a continuous positive semidefinite symmetric kernel with supxXk(x,x)<\sup_{x \in \mathcal{X}} |k(x, x)| < \infty. Let FF be the class of kernel expansions with bounded reproducing kernel Hilbert space norm: F={xi=1mαik(x,xi):mN,xiX,i,j=1mαiαjk(xi,xj)B2}.F = \left\{ x \mapsto \sum_{i=1}^m \alpha_i k(x, x_i) : m \in \mathbb{N}, x_i \in \mathcal{X}, \sum_{i,j=1}^m \alpha_i \alpha_j k(x_i, x_j) \le B^2 \right\}.

    For any sample X1,,XnXX_1, \dots, X_n \in \mathcal{X}, the empirical Gaussian and Rademacher complexities satisfy G^n(F)2Bni=1nk(Xi,Xi),R^n(F)2Bni=1nk(Xi,Xi),\hat{G}_n(F) \le \frac{2B}{n} \sqrt{\sum_{i=1}^n k(X_i, X_i)}, \qquad \hat{R}_n(F) \le \frac{2B}{n} \sqrt{\sum_{i=1}^n k(X_i, X_i)}, and their expected complexities satisfy Rn(F)2BE[k(X,X)]n,Gn(F)2BE[k(X,X)]n.R_n(F) \le 2B \sqrt{\frac{\mathbb{E}[k(X, X)]}{n}}, \qquad G_n(F) \le 2B \sqrt{\frac{\mathbb{E}[k(X, X)]}{n}}.

    Furthermore, for any margin parameter γ>0\gamma > 0, defining the ramp margin cost function ϕ:R[0,1]\phi: \mathbb{R} \to [0, 1] as ϕ(α)=1\phi(\alpha) = 1 for α0\alpha \le 0, ϕ(α)=1α/γ\phi(\alpha) = 1 - \alpha/\gamma for 0<αγ0 < \alpha \le \gamma, and ϕ(α)=0\phi(\alpha) = 0 for α>γ\alpha > \gamma, with probability at least 1δ1 - \delta over an independent sample (X1,Y1),,(Xn,Yn)P(X_1, Y_1), \dots, (X_n, Y_n) \sim P, every function f(x)=i=1nαik(Xi,x)f(x) = \sum_{i=1}^n \alpha_i k(X_i, x) with i,j=1nαiαjk(Xi,Xj)B2\sum_{i,j=1}^n \alpha_i \alpha_j k(X_i, X_j) \le B^2 satisfies P(Yf(X)0)1ni=1nϕ(Yif(Xi))+4Bγni=1nk(Xi,Xi)+(8γ+1)ln(4/δ)2n.\mathbb{P}(Y f(X) \le 0) \le \frac{1}{n}\sum_{i=1}^n \phi(Y_i f(X_i)) + \frac{4B}{\gamma n} \sqrt{\sum_{i=1}^n k(X_i, X_i)} + \left(\frac{8}{\gamma} + 1\right)\sqrt{\frac{\ln(4/\delta)}{2n}}.

  7. Knowl 7 — Gaussian Complexity of Boolean Combinations and Leaf-Weighted Decision Tree Bounds

    theoretical result

    For any fixed boolean function g:{±1}k{±1}g: \{\pm 1\}^k \to \{\pm 1\} and classes F1,,FkF_1, \dots, F_k of {±1}\{\pm 1\}-valued functions, the expected Gaussian complexity satisfies Gn(g(F1,,Fk))2j=1kGn(Fj).G_n(g(F_1, \dots, F_k)) \le 2 \sum_{j=1}^k G_n(F_j).

    This yields a risk bound for decision trees: let HH be a base class of binary-valued decision functions defined on X\mathcal{X}, and let TT be the class of decision trees of depth at most dd with internal node decision functions from HH. Let (X1,Y1),,(Xn,Yn)(X_1, Y_1), \dots, (X_n, Y_n) be drawn independently from a distribution PP on X×{±1}\mathcal{X} \times \{\pm 1\}.

    For a tree tTt \in T, let P~n(l)\tilde{P}_n(l) denote the proportion of all training examples that reach leaf ll and are correctly classified by leaf ll's assigned label. Then, with probability at least 1δ1 - \delta over the sample, every decision tree tTt \in T having LL leaves satisfies Pr(Yt(X))P^n(Yt(X))+l=1Lmin(P~n(l),cdGn(H))+cln(L/δ)2n,\Pr(Y \neq t(X)) \le \hat{P}_n(Y \neq t(X)) + \sum_{l=1}^L \min\left( \tilde{P}_n(l), c d G_n(H) \right) + \sqrt{\frac{c \ln(L/\delta)}{2n}}, where cc is an absolute constant and P^n(Yt(X))=1ni=1n1(Yit(Xi))\hat{P}_n(Y \neq t(X)) = \frac{1}{n}\sum_{i=1}^n \mathbf{1}(Y_i \neq t(X_i)). The complexity penalty is bounded by O(dLGn(H))O(d L G_n(H)), but decreases substantially when many leaves capture few correctly classified training examples.

  8. Knowl 8 — Gaussian Complexity Bounds for Linear Function Classes and Neural Networks

    theoretical result

    Let F1\mathcal{F}_1 be the class of linear functions on Rk\mathbb{R}^k with unit 1\ell_1-norm weight vectors: F1={xwx:wRk,w11}.\mathcal{F}_1 = \{x \mapsto w \cdot x : w \in \mathbb{R}^k, \|w\|_1 \le 1\}. For any sample points x1,,xnRkx_1, \dots, x_n \in \mathbb{R}^k with xi=(xi1,,xik)x_i = (x_{i1}, \dots, x_{ik}), the empirical Gaussian complexity is bounded by G^n(F1)clnknmaxj,j(i=1n(xijxij)2)1/2,\hat{G}_n(\mathcal{F}_1) \le \frac{c \sqrt{\ln k}}{n} \max_{j, j'} \left( \sum_{i=1}^n (x_{ij} - x_{ij'})^2 \right)^{1/2}, where cc is an absolute constant and the maximum is taken over all coordinate index pairs j,j{1,,k}j, j' \in \{1, \dots, k\}.

    For a two-layer neural network class FF mapping Rk[1,1]\mathbb{R}^k \to [-1, 1] defined by F={xiwiσ(vix):w11,vi1B},F = \left\{ x \mapsto \sum_i w_i \sigma(v_i \cdot x) : \|w\|_1 \le 1, \|v_i\|_1 \le B \right\}, where the scalar activation function σ:R[1,1]\sigma: \mathbb{R} \to [-1, 1] is Lipschitz continuous with constant LL and satisfies σ(0)=0\sigma(0) = 0, the empirical Gaussian complexity satisfies G^n(F)cLBlnknmaxj,j(i=1n(xijxij)2)1/2.\hat{G}_n(F) \le \frac{c L B \sqrt{\ln k}}{n} \max_{j, j'} \left( \sum_{i=1}^n (x_{ij} - x_{ij'})^2 \right)^{1/2}.

  9. Knowl 9 — Relationships Between Maximum Discrepancy, Rademacher, and Gaussian Complexities

    theoretical result

    For any class FF of functions mapping from X\mathcal{X} to [1,1][-1, 1] and any sample size nn:

    1. Rademacher Complexity and Expected Discrepancy: The expected maximum discrepancy Dn(F)D_n(F) and expected Rademacher complexity Rn(F)R_n(F) satisfy Rn(F)222nDn(F)Rn(F)+42n.\frac{R_n(F)}{2} - 2\sqrt{\frac{2}{n}} \le D_n(F) \le R_n(F) + 4\sqrt{\frac{2}{n}}. If FF is closed under negation (fF    fFf \in F \implies -f \in F), the lower bound strengthens to Rn(F)42nDn(F).R_n(F) - 4\sqrt{\frac{2}{n}} \le D_n(F). Moreover, the empirical discrepancy D^n(F)\hat{D}_n(F) concentrates around its expectation: P(D^n(F)Dn(F)ϵ)2exp(ϵ2n2).\mathbb{P}(|\hat{D}_n(F) - D_n(F)| \ge \epsilon) \le 2\exp\left(-\frac{\epsilon^2 n}{2}\right).

    2. Rademacher and Gaussian Complexities: There exist absolute positive constants cc and CC such that for every function class FF and every integer nn, cRn(F)Gn(F)Cln(n)Rn(F).c R_n(F) \le G_n(F) \le C \ln(n) R_n(F).

  10. Knowl 10 — Classification Risk Bounds via Discrepancy, Rademacher Complexity, and Empirical VC Dimensions

    theoretical result

    Let FF be a class of {±1}\{\pm 1\}-valued functions on X\mathcal{X}, and let (X1,Y1),,(Xn,Yn)(X_1, Y_1), \dots, (X_n, Y_n) be training samples drawn independently according to a probability distribution PP on X×{±1}\mathcal{X} \times \{\pm 1\}.

    1. Classification Risk Bounds: With probability at least 1δ1 - \delta over samples of size nn, every fFf \in F satisfies P(Yf(X))P^n(Yf(X))+D^n(F)+9ln(1/δ)2n,\mathbb{P}(Y \neq f(X)) \le \hat{P}_n(Y \neq f(X)) + \hat{D}_n(F) + \sqrt{\frac{9 \ln(1/\delta)}{2n}}, and also P(Yf(X))P^n(Yf(X))+Rn(F)2+ln(1/δ)2n,\mathbb{P}(Y \neq f(X)) \le \hat{P}_n(Y \neq f(X)) + \frac{R_n(F)}{2} + \sqrt{\frac{\ln(1/\delta)}{2n}}, where P^n(Yf(X))=1ni=1n1(Yif(Xi))\hat{P}_n(Y \neq f(X)) = \frac{1}{n} \sum_{i=1}^n \mathbf{1}(Y_i \neq f(X_i)).

    2. Empirical VC-Dimension and VC-Entropy Upper Bounds: For a fixed sample X1,,XnX_1, \dots, X_n, let FXi={(f(X1),,f(Xn)):fF}F|_{X_i} = \{(f(X_1), \dots, f(X_n)) : f \in F\}. Let d=VCdim(FXi)d = \mathrm{VCdim}(F|_{X_i}) denote the empirical VC-dimension and E=log2FXiE = \log_2 |F|_{X_i}| denote the empirical VC-entropy. Then the empirical Gaussian complexity satisfies G^n(F)=O(dn)andG^n(F)=O(En).\hat{G}_n(F) = O\left(\sqrt{\frac{d}{n}}\right) \quad \text{and} \quad \hat{G}_n(F) = O\left(\sqrt{\frac{E}{n}}\right). Hence, the Rademacher and Gaussian complexity risk bounds are at least as tight as classical VC-dimension bounds while adapting to the empirical distribution of the data.

Coverage note — Bounds relating empirical Gaussian complexity to empirical fat-shattering dimensions (Theorem 10) were omitted because they adapt prior results from Mendelson (2002); all other core contributions are included.

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Citation

MLA
Bartlett, P. L., and S. Mendelson. “Rademacher and Gaussian Complexities: Risk Bounds and Structural Results”. Lecture Notes in Computer Science, Springer Berlin Heidelberg, 2001, pp. 224–40, https://doi.org/10.1007/3-540-44581-1_15.
APA
Bartlett, P. L., & Mendelson, S. (2001). Rademacher and Gaussian Complexities: Risk Bounds and Structural Results. In Lecture Notes in Computer Science (pp. 224–240). Springer Berlin Heidelberg. https://doi.org/10.1007/3-540-44581-1_15
Chicago
Bartlett, P. L., and S. Mendelson. 2001. “Rademacher and Gaussian Complexities: Risk Bounds and Structural Results”. In Lecture Notes in Computer Science. Springer Berlin Heidelberg. https://doi.org/10.1007/3-540-44581-1_15.
Harvard
Bartlett, P.L. and Mendelson, S. (2001) “Rademacher and Gaussian Complexities: Risk Bounds and Structural Results”, Lecture Notes in Computer Science. Springer Berlin Heidelberg, pp. 224–240. Available at: https://doi.org/10.1007/3-540-44581-1_15.
Vancouver
1. Bartlett PL, Mendelson S (2001) Rademacher and Gaussian Complexities: Risk Bounds and Structural Results. In: Lecture Notes in Computer Science. Springer Berlin Heidelberg, pp 224–240

BibTeX

@inbook{Bartlett_2001, title={Rademacher and Gaussian Complexities: Risk Bounds and Structural Results}, ISBN={9783540445814}, ISSN={0302-9743}, url={http://dx.doi.org/10.1007/3-540-44581-1_15}, DOI={10.1007/3-540-44581-1_15}, booktitle={Computational Learning Theory}, publisher={Springer Berlin Heidelberg}, author={Bartlett, Peter L. and Mendelson, Shahar}, year={2001}, pages={224–240} }
Metadata:Crossref

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