The Numerical Stability of Hyperbolic Representation Learning

Gal MishneZhengchao WanYusu WangSheng Yang

article2023ICML67 citations

Analyzes the representation and optimization trade-offs between Poincaré and Lorentz models under standard floating-point precision, presenting a Euclidean parametrization that prevents numerical instabilities in hyperbolic machine learning.

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Hyperbolic machine learning has become an essential technique for analyzing hierarchical and tree-like data across domains such as natural language processing, recommendation systems, and genomics. Hyperbolic space naturally accommodates branching structures with low distortion because its volume expands exponentially. However, this same geometric property creates severe numerical instability during computational modeling. In standard 64-bit floating-point arithmetic, existing implementations routinely encounter vanishing gradients, rounding limits, and invalid calculations (NaN errors), forcing systems to constrain learning parameters or halt entirely.

The article systematically evaluates the numerical representation limits and optimization dynamics of the two most common hyperbolic frameworks—the Poincaré ball and the Lorentz model. It demonstrates mathematically and empirically why standard models fail, introduces a robust Euclidean parametrization to resolve these trade-offs, and extends this framework to hyperbolic support vector machines for classification tasks.

To conduct this evaluation, the authors performed theoretical mathematical analyses of coordinate capacities and gradient behaviors in 64-bit precision. They supplemented this theory with empirical validation on eight simulated tree-embedding datasets and six real-world classification benchmarks, including image datasets (CIFAR-10, Fashion-MNIST) and multiple single-cell RNA biological datasets. Performance was evaluated across metric distortion, gradient norms, embedding spread, classification accuracy, and macro F1 scores.

The findings establish that under 64-bit arithmetic, the Poincaré model has a wider representation capacity radius of approximately 38 from the origin before points collapse to the boundary, compared to a radius of approximately 19 for the Lorentz model. Conversely, the Lorentz model is substantially superior in optimization; the Poincaré model suffers from severe gradient vanishing near the boundary because its gradient update terms scale at second-order decay (10^-2k) versus first-order decay (10^-k) in Lorentz. The proposed Euclidean feature parametrization successfully combines the benefits of both by eliminating numerical capacity boundaries entirely while maintaining first-order optimization dynamics comparable to Lorentz. In empirical tree embeddings, the Euclidean approach achieved lower average distortion (reaching 1.0019–1.0292) and substantially larger embedding diameters (around 8.8–19.8) compared to the restricted Poincaré embeddings (around 4.2–6.4). Finally, applying this parametrization to hyperbolic hyperplanes removed non-convex constraints, creating a reformulated classifier (LSVMPP) that outperformed standard Euclidean, Poincaré, and Lorentz baselines across almost all benchmarks (e.g., reaching 89.49% on Fashion-MNIST and 62.64% on the Paul dataset).

These results demonstrate that practitioner difficulties with hyperbolic learning stem from structural flaws in coordinate optimization rather than data quality. By utilizing Euclidean parametrizations, engineering teams can eliminate catastrophic training collapses, avoid artificial thresholding hacks, and improve model accuracy on complex hierarchical data without incurring custom ultra-high-precision hardware overhead.

Engineering and research teams should adopt Euclidean parametrizations as the default training proxy for hyperbolic representation learning and hyperbolic support vector machines. Additionally, practitioners employing multi-class scaling should use hyperbolic signed distance transformations (arcsinh adjustments) to calibrate prediction confidence effectively. Before broad deployment, development teams should conduct pilots on larger-scale networks, as accelerated momentum methods in hyperbolic spaces still require further investigation.

The article's conclusions are supported with high confidence by both formal proofs and consistent multi-domain experiments. However, practitioners should note that computing certain derived functions, such as pairwise hyperbolic distances between distant points, may still encounter standard precision limits, warranting careful boundary checks in production environments.

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Abstract

The hyperbolic space is widely used for representing hierarchical datasets due to its ability to embed trees with small distortion. However, this property comes at a price of numerical instability such that training hyperbolic learning models will sometimes lead to catastrophic NaN problems, encountering unrepresentable values in floating point arithmetic. In this work, we analyze the limitations of two popular models for the hyperbolic space, namely, the Poincaré ball and the Lorentz model. We find that, under the 64 bit arithmetic system, the Poincaré ball has a relatively larger capacity than the Lorentz model for correctly representing points. However, the Lorentz model is superior to the Poincaré ball from the perspective of optimization, which we theoretically validate. To address these limitations, we identify one Euclidean parametrization of the hyperbolic space which can alleviate these issues. We further extend this Euclidean parametrization to hyperbolic hyperplanes and demonstrate its effectiveness in improving the performance of hyperbolic SVM.

Table of Contents

  • 1. Introduction
  • 2. Preliminary
  • 3. Comparing Lorentz and Poincaré Models
  • 3.1. Optimization
  • 4. Euclidean Parametrization of Hyperbolic Space
  • 4.1. Feature Parametrization
  • 4.2. Hyperplane Parametrization
  • 4.2.1. A New Formulation of Hyperbolic SVM
  • 5. Experiments
  • 5.1. Hyperbolic Embeddings
  • 5.2. Hyperbolic SVM Models
  • 6. Discussions
  • Acknowledgements
  • References
  • A. Proofs
  • A.1. Proof of Proposition 3.1
  • A.2. Proof of Proposition 3.2
  • A.3. Proof of Proposition 3.3
  • A.4. Proof of Lemma 3.4
  • A.5. Proof of Theorem 3.5
  • A.6. Proof of Theorem 4.2
  • A.7. Derivation of Equation (12)
  • B. Tree Optimization
  • B.1. Synthetic Data Generating Processing
  • B.2. Full Results
  • C. More on SVM
  • C.1. Overview of SVM in Binary Classification
  • C.2. Multiclass Classification Using SVM: Platt Scaling
  • C.2.1. Adaptation of Platt Scaling on Hyperbolic Spaces
  • C.3. Hyperbolic SVM Implementation and Hyperparameters
  • C.4. Details of Synthetic Data Generation
  • C.5. Full Results

Knowls

  1. Knowl 1 — Float64 representation capacity differs sharply between the Poincaré and Lorentz models

    theoretical result

    Under 64-bit floating-point arithmetic, the largest reliably representable radius from the origin is approximately 3838 in the Poincaré ball and 1919 in the Lorentz model. For a Poincaré point xx with Euclidean norm ∥x∥=1−10−k\|x\|=1-10^{-k}, its hyperbolic distance from the origin is d(0,x)=ln⁡(10)k+ln⁡(2)+O(10−k)d(0,x)=\ln(10)k+\ln(2)+O(10^{-k}). In Float64, 1−10−k1-10^{-k} rounds to 11 when 10−k≲2−53≈10−1610^{-k}\lesssim 2^{-53}\approx 10^{-16}, giving a maximum useful kk of about 1616 and radius about 3838. For a Lorentz point x=(x0,x1,…,xn)x=(x_0,x_1,\ldots,x_n) with x0=10kx_0=10^k, the distance from the Lorentz origin is d(0ˉ,x)=ln⁡(10)k+ln⁡(2)+O(10−2k)d(\bar 0,x)=\ln(10)k+\ln(2)+O(10^{-2k}). Around x0=108x_0=10^8, floating-point arithmetic cannot distinguish x02−1x_0^2-1 from x02x_0^2, compromising the defining Minkowski norm constraint and yielding the approximate radius limit 1919.

    The two limitations have different operational character. In the Poincaré ball, points beyond the threshold round to the boundary, so subsequent manifold operations are unavailable; this is a hard limit. In the Lorentz model, the time coordinate can become numerically unverifiable while the spatial coordinates remain available for further computations, making the limit comparatively soft. Equivalently, measuring capacity in the tangent space at the origin, the exponential maps can represent radial tangent vectors only up to approximately 3838 for the Poincaré model and 1919 for the Lorentz model under this arithmetic.

  2. Knowl 2 — Poincaré-coordinate optimization suffers stronger gradient vanishing than Lorentz-coordinate optimization

    theoretical result

    Let ff be a differentiable objective on hyperbolic space, represented in the Poincaré ball by ff and in the Lorentz model by its isometric counterpart. Exact Riemannian gradient descent in the two models gives corresponding updates under the isometry, but the coordinate magnitudes used in floating-point computation differ. If a Poincaré point xx satisfies ∥x∥=1−δ\|x\|=1-\delta for small δ>0\delta>0, then the Euclidean coordinate magnitude of its Poincaré Riemannian gradient is Ω(δ2∥∇f(x)∥)\Omega(\delta^2\|\nabla f(x)\|), whereas the Lorentz-coordinate gradient magnitude is O(∥∇f(x)∥)O(\|\nabla f(x)\|).

    For a radial example, take x=(1−10−k,0,…,0)x=(1-10^{-k},0,\ldots,0), assume ∇f(x)=(∂1f(x),0,…,0)\nabla f(x)=(\partial_1 f(x),0,\ldots,0) with ∂1f(x)<0\partial_1 f(x)<0, let E=∥∇f(x)∥E=\|\nabla f(x)\|, and use learning rate η>0\eta>0. The respective one-step updates have expansions

    exp⁡x(−η∇Df(x))=(1−10−k+O(ηE10−2k),0,…,0),\exp_x(-\eta\nabla^{D}f(x))=(1-10^{-k}+O(\eta E10^{-2k}),0,\ldots,0), exp⁡y(−η∇Lg(y))=10k(1−1210−k+ηE10−k+O(ηE10−2k),  1−1210−k+ηE10−k+O(ηE10−2k),  0,…,0),\exp_y(-\eta\nabla^{L}g(y))=10^k\big(1-\tfrac12 10^{-k}+\eta E10^{-k}+O(\eta E10^{-2k}),\;1-\tfrac12 10^{-k}+\eta E10^{-k}+O(\eta E10^{-2k}),\;0,\ldots,0\big),

    where yy is the Lorentz point corresponding to xx, and DD and LL denote the Poincaré and Lorentz models. For bounded EE and η=1\eta=1, the Poincaré update adds a term of order 10−2k10^{-2k} to a coordinate near 11, while the Lorentz update changes coordinates at relative order 10−k10^{-k}. At k=8k=8, the Poincaré update is about Float64 rounding precision and can be lost; the Lorentz update is less affected by gradient vanishing. Thus, although the Poincaré model has greater point-representation capacity, much of its outer region cannot be effectively used by gradient optimization.

  3. Knowl 3 — A Euclidean tangent-space parametrization represents hyperbolic features by unconstrained vectors

    model/method

    For a hyperbolic point represented by z∈Rnz\in\mathbb{R}^n, the paper parametrizes corresponding Poincaré-ball and Lorentz-model features by the exponential maps at their origins:

    FD(z)=tanh⁡ ⁣(∥z∥2)z∥z∥,FL(z)=(cosh⁡(∥z∥),  sinh⁡(∥z∥)z∥z∥).F_D(z)=\tanh\!\left(\frac{\|z\|}{2}\right)\frac{z}{\|z\|}, \qquad F_L(z)=\left(\cosh(\|z\|),\;\sinh(\|z\|)\frac{z}{\|z\|}\right).

    At z=0z=0, both expressions are defined by continuity. The Poincaré origin is 00 and the Lorentz origin is 0ˉ=(1,0,…,0)\bar 0=(1,0,\ldots,0). These maps identify the two model representations of the same hyperbolic point and preserve radial distance: for x=FD(z)x=F_D(z) and y=FL(z)y=F_L(z), dD(0,x)=dL(0ˉ,y)=∥z∥d_D(0,x)=d_L(\bar 0,y)=\|z\|. The paper uses the unconstrained Euclidean vector zz as the trainable feature representation, avoiding the finite-radius constraint on the stored feature coordinates in the two manifold models. This parametrization is a diffeomorphic coordinate system, not a representation preserving the Riemannian metric in all directions; numerical evaluation of hyperbolic quantities derived from these coordinates can still be problematic.

  4. Knowl 4 — Euclidean parametrization mitigates Poincaré gradient vanishing

    theoretical result

    Let h(z)=f(FD(z))h(z)=f(F_D(z)) be a hyperbolic objective expressed using the Euclidean feature parametrization FDF_D, and consider the radial point x=(1−δ,0,…,0)x=(1-\delta,0,\ldots,0) with δ=10−k\delta=10^{-k} and z=FD−1(x)=(2arctanh⁡(1−δ),0,…,0)z=F_D^{-1}(x)=(2\operatorname{arctanh}(1-\delta),0,\ldots,0). Under the radial-gradient assumptions ∇f(x)=(∂1f(x),0,…,0)\nabla f(x)=(\partial_1f(x),0,\ldots,0) and ∂1f(x)<0\partial_1f(x)<0, set E=∥∇f(x)∥E=\|\nabla f(x)\|. The Euclidean gradient satisfies ∥∇h(z)∥=Ω(δE)\|\nabla h(z)\|=\Omega(\delta E), rather than the Ω(δ2E)\Omega(\delta^2 E) scaling of the Poincaré Riemannian gradient. A gradient step with learning rate η\eta has first coordinate

    z1−η(∇h(z))1=ln⁡(10)k+ln⁡(2)+(ηE−12)10−k+O(10−2k).z_1-\eta(\nabla h(z))_1=\ln(10)k+\ln(2)+(\eta E-\tfrac12)10^{-k}+O(10^{-2k}).

    The Jacobian of the exponential-map parametrization cancels one power of the small boundary factor responsible for Poincaré gradient vanishing. For points within the Lorentz model's practical Float64 range, the Euclidean-coordinate update has behavior similar to Lorentz optimization and is less prone to vanishing than direct Poincaré optimization.

  5. Knowl 5 — Hyperbolic hyperplanes admit an unconstrained Euclidean parametrization

    model/method

    In the Lorentz model, write a point as x=(x0,xr)∈Rn+1x=(x_0,x_r)\in\mathbb{R}^{n+1}, where xr∈Rnx_r\in\mathbb{R}^n, and use the Minkowski product [u,v]=−u0v0+⟨ur,vr⟩[u,v]=-u_0v_0+\langle u_r,v_r\rangle. For parameters a∈Ra\in\mathbb{R} and z∈Rnz\in\mathbb{R}^n, the paper parametrizes a hyperplane by transporting a tangent vector from the Lorentz origin to a point pp:

    p=(cosh⁡(a),sinh⁡(a)z∥z∥),w=(sinh⁡(a)∥z∥,cosh⁡(a)z).p=\left(\cosh(a),\sinh(a)\frac{z}{\|z\|}\right), \qquad w=\left(\sinh(a)\|z\|,\cosh(a)z\right).

    The resulting hyperplane is

    H~z,a={x∈Ln:cosh⁡(a)⟨z,xr⟩=sinh⁡(a)∥z∥x0}.\widetilde H_{z,a}=\left\{x\in L^n:\cosh(a)\langle z,x_r\rangle=\sinh(a)\|z\|x_0\right\}.

    Here pp is at distance ∣a∣|a| from the origin in the direction of zz, and ww has Lorentz tangent norm ∥z∥\|z\|. The hyperplane equation remains well-defined for z=0z=0, where it degenerates to the whole space. Unlike optimizing directly over a Lorentz tangent vector, this parametrization places no constraint such as [w,w]>0[w,w]>0 on the optimization variables.

  6. Knowl 6 — LSVMPP reformulates Lorentz SVM using the Euclidean hyperplane coordinates

    model/method

    For Lorentz-model training examples xi=(xi0,xir)∈Lnx_i=(x_{i0},x_{ir})\in L^n with binary labels yi∈{−1,1}y_i\in\{-1,1\}, the paper substitutes the Euclidean hyperplane parameters z∈Rnz\in\mathbb{R}^n and a∈Ra\in\mathbb{R} into the soft-margin Lorentz SVM objective. The resulting LSVMPP optimization problem is

    min⁡z,a  12∥z∥2+C∑i=1NlL ⁣(yi[sinh⁡(a)∥z∥xi0−cosh⁡(a)⟨z,xir⟩]),\min_{z,a}\;\frac12\|z\|^2+C\sum_{i=1}^N l_L\!\left(y_i\left[\sinh(a)\|z\|x_{i0}-\cosh(a)\langle z,x_{ir}\rangle\right]\right),

    where NN is the number of examples, C>0C>0 controls the misclassification penalty, and lL(u)=max⁡(0,arcsinh⁡(1)−arcsinh⁡(u))l_L(u)=\max(0,\operatorname{arcsinh}(1)-\operatorname{arcsinh}(u)). This removes the nonconvex feasibility constraint on the Lorentz hyperplane vector, although the resulting objective remains nonconvex. For classification probability calibration, the paper also uses the normed signed hyperplane-distance score arcsinh⁡(−[w,x]/∥w∥L)\operatorname{arcsinh}(-[w,x]/\|w\|_L) as input to Platt scaling, rather than using the raw Minkowski inner product alone.

  7. Knowl 7 — Tree embeddings show that Euclidean-parametrized and Lorentz training outperform direct Poincaré training

    data/table

    Eight simulated trees were embedded using direct Poincaré optimization (D2D^2), direct Lorentz optimization (L2L^2), or Euclidean optimization of tangent-space coordinates with hyperbolic distances (E2E^2). The raw baseline measures Euclidean distances between the original tree coordinates. Each tree was initialized, centered, and normalized to a unit square. Training minimized the squared discrepancy between normalized tree and embedding pairwise distances, using learning rate 11 for 30,00030{,}000 epochs; the manifold models used Riemannian SGD and the Euclidean model used SGD. Average distortion δ\delta is the product of mean contraction and expansion ratios, max distortion δmax⁡\delta^{\max} uses the corresponding supremum, and dd is embedding diameter. Lower distortion is better; larger diameter indicates a more spread-out embedding.

    The Euclidean and Lorentz models have comparable results, with Euclidean optimization usually slightly better; both generally improve over the Poincaré model. In particular, Poincaré embeddings have much smaller diameters, consistent with their optimization getting stuck before using the available hyperbolic range.

    Tree Manifold δ\delta δmax⁡\delta^{\max} dd
    1 raw 1.1954 10.6062 2.8284
    1 D2D^2 1.0462 4.0546 4.8740
    1 L2L^2 1.0176 2.4511 10.1827
    1 E2E^2 1.0157 2.3158 10.9019
    2 raw 1.1186 14.1421 2.2361
    2 D2D^2 1.0589 7.1435 4.9757
    2 L2L^2 1.0180 3.2803 10.6719
    2 E2E^2 1.0134 2.7408 11.4504
    3 raw 1.0511 3.0000 2.0396
    3 D2D^2 1.0321 3.3830 6.3564
    3 L2L^2 1.0190 2.5506 9.6830
    3 E2E^2 1.0174 2.4350 10.2328
    4 raw 1.1539 19.0000 2.8284
    4 D2D^2 1.0754 14.1074 5.0453
    4 L2L^2 1.0421 8.2933 10.4028
    4 E2E^2 1.0292 6.8504 12.7596
    5 raw 1.3349 12.7279 1.4142
    5 D2D^2 1.0176 2.0321 4.2523
    5 L2L^2 1.0029 1.2829 7.3850
    5 E2E^2 1.0019 1.1997 8.8504
    6 raw 1.5080 88.8552 1.4142
    6 D2D^2 1.1243 50.4524 4.3168
    6 L2L^2 1.0392 21.9948 8.9204
    6 E2E^2 1.0269 22.3743 9.8190
    7 raw 1.2108 17.7132 0.8321
    7 D2D^2 1.2145 8.6454 5.0657
    7 L2L^2 1.0166 3.7655 19.1703
    7 E2E^2 1.0100 1.7825 19.8481
    8 raw 1.1421 10.7807 0.9220
    8 D2D^2 1.0324 9.7552 4.5670
    8 L2L^2 1.0157 9.2790 8.8324
    8 E2E^2 1.0148 8.4500 9.1712
  8. Knowl 8 — Hyperbolic SVM evaluation compares four classifiers across synthetic and real data

    experimental setup

    The classification experiments compare Euclidean SVM (ESVM), Lorentz SVM (LSVM), Poincaré SVM with a precomputed tangent reference point (PSVM), and the proposed parametrized Lorentz SVM (LSVMPP). The six synthetic datasets comprise three Gaussian mixtures and three explicit trees. Each Gaussian-mixture dataset contains 1,200 points in the Poincaré disk, formed by mapping two-dimensional Euclidean samples through the hyperbolic feature parametrization; the number of equally sized labeled clusters is k∈{3,5,10}k\in\{3,5,10\}, with centroids sampled from N(0,1.5I2)\mathcal N(0,1.5I_2) and noise from N(0,I2)\mathcal N(0,I_2). For each explicit-tree dataset, a node is selected at random, its descendants form the positive class, and all other nodes form the negative class.

    The six real datasets are CIFAR-10, Fashion-MNIST, Paul myeloid progenitors (19 classes), Olsson single-cell RNA sequencing (8 classes), Krumsiek simulated myeloid progenitors (11 classes), and Moignard blood-cell development (7 classes). Their points were embedded in the curvature-1 Poincaré disk. The evaluation used one-vs-all classifiers with Platt scaling; each fixed train-test split was run five times, with accuracy and macro F1 reported. The CIFAR-10, Fashion-MNIST, and Olsson splits followed the established split used by the PSVM evaluation; other real datasets used stratified 75%/25% splits. ESVM and PSVM performed best with C=5C=5 and learning rate 0.0010.001; LSVM and LSVMPP generally used C=0.5C=0.5, learning rate around 10−1010^{-10}, and 500 epochs.

  9. Knowl 9 — LSVMPP improves results on most, but not all, real and synthetic SVM datasets

    empirical result

    On the six real datasets, LSVMPP with the arcsinh distance-based Platt score has the highest accuracy and macro F1 on CIFAR-10, Fashion-MNIST, Paul, and Krumsiek. PSVM leads on Olsson, while ESVM leads on Moignard. The following values are mean accuracy (percent) and macro F1, reported as mean ±\pm standard deviation:

    Dataset Method Accuracy (%) Macro F1
    CIFAR-10 ESVM 91.88 ±\pm 0.00 0.9191 ±\pm 0.00
    LSVM 91.88 ±\pm 0.00 0.9189 ±\pm 0.00
    PSVM 91.81 ±\pm 0.00 0.9182 ±\pm 0.00
    LSVMPP (raw) 91.94 ±\pm 0.00 0.9195 ±\pm 0.00
    LSVMPP (arcsinh) 91.96 ±\pm 0.00 0.9197 ±\pm 0.00
    Fashion-MNIST ESVM 86.37 ±\pm 0.00 0.8665 ±\pm 0.00
    LSVM 71.59 ±\pm 0.07 0.6588 ±\pm 0.08
    PSVM 86.57 ±\pm 0.00 0.8665 ±\pm 0.00
    LSVMPP (raw) 89.35 ±\pm 0.00 0.8939 ±\pm 0.00
    LSVMPP (arcsinh) 89.49 ±\pm 0.00 0.8955 ±\pm 0.00
    Paul ESVM 55.05 ±\pm 0.00 0.4073 ±\pm 0.00
    LSVM 58.36 ±\pm 0.07 0.4517 ±\pm 0.00
    PSVM 55.25 ±\pm 0.00 0.3802 ±\pm 0.00
    LSVMPP (raw) 62.55 ±\pm 0.14 0.4579 ±\pm 0.01
    LSVMPP (arcsinh) 62.64 ±\pm 0.05 0.5024 ±\pm 0.00
    Olsson ESVM 72.72 ±\pm 0.00 0.4922 ±\pm 0.00
    LSVM 81.82 ±\pm 0.00 0.7542 ±\pm 0.00
    PSVM 88.63 ±\pm 0.00 0.8793 ±\pm 0.00
    LSVMPP (raw) 80.91 ±\pm 0.45 0.7142 ±\pm 0.03
    LSVMPP (arcsinh) 84.09 ±\pm 0.00 0.8429 ±\pm 0.00
    Krumsiek ESVM 82.19 ±\pm 0.00 0.6770 ±\pm 0.00
    LSVM 85.62 ±\pm 0.39 0.6933 ±\pm 0.92
    PSVM 84.06 ±\pm 0.00 0.6908 ±\pm 0.00
    LSVMPP (raw) 83.75 ±\pm 0.28 0.6403 ±\pm 0.01
    LSVMPP (arcsinh) 86.25 ±\pm 0.00 0.7079 ±\pm 0.00
    Moignard ESVM 67.78 ±\pm 0.00 0.5934 ±\pm 0.00
    LSVM 64.88 ±\pm 0.38 0.5502 ±\pm 0.22
    PSVM 60.77 ±\pm 0.00 0.5167 ±\pm 0.00
    LSVMPP (raw) 65.77 ±\pm 0.13 0.5671 ±\pm 0.00
    LSVMPP (arcsinh) 65.22 ±\pm 0.63 0.5719 ±\pm 0.02

    The pattern is not uniform on synthetic data either: LSVMPP reaches 100.00% accuracy and 1.0000 macro F1 on one explicit-tree dataset, and performs strongly on several others, but other methods tie or lead on some synthetic cases. The authors therefore report an overall advantage on most tested datasets, not universal dominance.

  10. Knowl 10 — The Euclidean parametrization does not remove numerical instability from all hyperbolic computations

    limitation

    The paper's Euclidean feature coordinates avoid a finite-radius limit on the stored parameter vector, but this does not guarantee numerical stability for every computation induced by hyperbolic geometry. In particular, evaluating quantities such as hyperbolic distances between parametrized points may still produce numerical problems. The parametrization also does not preserve the full Riemannian structure, so Euclidean optimization is a proxy for optimizing hyperbolic objectives rather than Riemannian gradient descent itself.

Coverage note — Proof derivations, background geometry, visualization-only material, and secondary implementation details were omitted; the main capacity, optimization, parametrization, SVM, and experimental contributions are represented.

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Citation

MLA
Mishne, G., et al. “The Numerical Stability of Hyperbolic Representation Learning”. International Conference on Machine Learning, vol. 202, 2023, pp. 24925–49, https://proceedings.mlr.press/v202/mishne23a.html.
APA
Mishne, G., Wan, Z., Wang, Y., & Yang, S. (2023). The Numerical Stability of Hyperbolic Representation Learning. International Conference on Machine Learning, 202, 24925–24949. https://proceedings.mlr.press/v202/mishne23a.html
Chicago
Mishne, G., Z. Wan, Y. Wang, and S. Yang. 2023. “The Numerical Stability of Hyperbolic Representation Learning”. International Conference on Machine Learning 202: 24925–49. https://proceedings.mlr.press/v202/mishne23a.html.
Harvard
Mishne, G. et al. (2023) “The Numerical Stability of Hyperbolic Representation Learning”, International Conference on Machine Learning. PMLR, pp. 24925–24949. Available at: https://proceedings.mlr.press/v202/mishne23a.html.
Vancouver
1. Mishne G, Wan Z, Wang Y, Yang S (2023) The Numerical Stability of Hyperbolic Representation Learning. In: International Conference on Machine Learning. PMLR, pp 24925–24949

BibTeX

@InProceedings{pmlr-v202-mishne23a,
  title = 	 {The Numerical Stability of Hyperbolic Representation Learning},
  author =       {Mishne, Gal and Wan, Zhengchao and Wang, Yusu and Yang, Sheng},
  booktitle = 	 {Proceedings of the 40th International Conference on Machine Learning},
  pages = 	 {24925--24949},
  year = 	 {2023},
  editor = 	 {Krause, Andreas and Brunskill, Emma and Cho, Kyunghyun and Engelhardt, Barbara and Sabato, Sivan and Scarlett, Jonathan},
  volume = 	 {202},
  series = 	 {Proceedings of Machine Learning Research},
  month = 	 {23--29 Jul},
  publisher =    {PMLR},
  pdf = 	 {https://proceedings.mlr.press/v202/mishne23a/mishne23a.pdf},
  url = 	 {https://proceedings.mlr.press/v202/mishne23a.html},
  abstract = 	 {The hyperbolic space is widely used for representing hierarchical datasets due to its ability to embed trees with small distortion. However, this property comes at a price of numerical instability such that training hyperbolic learning models will sometimes lead to catastrophic NaN problems, encountering unrepresentable values in floating point arithmetic. In this work, we analyze the limitations of two popular models for the hyperbolic space, namely, the Poincaré ball and the Lorentz model. We find that, under the 64-bit arithmetic system, the Poincaré ball has a relatively larger capacity than the Lorentz model for correctly representing points. However, the Lorentz model is superior to the Poincaré ball from the perspective of optimization, which we theoretically validate. To address these limitations, we identify one Euclidean parametrization of the hyperbolic space which can alleviate these issues. We further extend this Euclidean parametrization to hyperbolic hyperplanes and demonstrate its effectiveness in improving the performance of hyperbolic SVM.}
}
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