Random Dot Product Graphs as Dynamical Systems: Limitations and Opportunities
Abstract
Can we learn the differential equations governing the evolution of a temporal network? We investigate this within Random Dot Product Graphs (RDPGs), where each network snapshot is generated from latent positions evolving under unknown dynamics. We identify three fundamental obstructions: gauge freedom from rotational ambiguity in latent positions, realizability constraints from the manifold structure of the probability matrix, and trajectory recovery artifacts from spectral embedding. We develop a geometric framework based on principal fiber bundles that formalizes these obstructions. We characterize invisible dynamics as exactly the skew-symmetric generators, and show the realizable tangent space has dimension . An holonomy dichotomy emerges: polynomial dynamics have commuting generators, stationary eigenvectors, and trivial holonomy, making gauge alignment purely statistical; Laplacian dynamics satisfy a non-commutativity criterion producing nontrivial holonomy, with curvature weighted by linking gauge sensitivity to the spectral gap. In this yields full restricted holonomy ; for generic full remains conjectural. Cram'er--Rao lower bounds reveal that the same spectral gap controlling curvature and injectivity simultaneously controls Fisher information, so geometric and statistical difficulty are inextricable. We prove an identifiability principle: symmetric dynamics cannot absorb skew-symmetric gauge contamination, so dynamics structure can resolve gauge ambiguity. We demonstrate this constructively with anchor-based alignment and a UDE pipeline recovering vector fields from noisy graph sequences. Yet finite-sample interactions between noise, gauge, and dynamics expressiveness remain beyond the asymptotic theory. We frame this gap as an open challenge.
Figures & tables
| Result | Status | Scope |
|---|---|---|
| Theorem 1 | Proved | Full-rank latent states |
| Proposition 9 | Proved | Horizontal symmetric families |
| Proposition 11 | Proved | Local nonzero commutator criterion |
| Corollary 3 | Proved | Linear dynamics |
| Proposition 14 | Proved | Polynomial dynamics + regularity assumptions |
| Theorem 4 | Proved | Symmetric-generator identifiability |
| Approach | Smoothness | Dynamical Consistency |
|---|---|---|
| Hierarchical GP prior | Yes ( ) | No: interpolation only |
| SDE | No (Hölder ) | Yes, as |
| Neural ODE | Yes ( ) | Yes (by construction) |
| GP-ODE (NPODE) ( Heinonen et al., 2018 ) | Yes ( ) | Yes: learns as GP |
| Structure-constrained (ours) | Yes | Yes: family enforced |
| Family | Form | Horizontal? | Parameters |
|---|---|---|---|
| Linear symmetric | , | Always | |
| Polynomial | Always | ||
| Laplacian | Always | 0 (fixed) | |
| Message-passing | If symmetric | ||
| Centroid circulation | No | ||
| General linear | If sym. |
Latent Dynamics Modeling
Latent dynamics modeling learns compact hidden-state representations and transition rules to predict, explain, and control evolving systems.
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