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Gaussian Graphical Learning via PSD Constraint for Blockwise Missing Multimodal Data
Proceedings of the 42nd Conference on Uncertainty in Artificial Intelligence, PMLR 337:1748-1768, 2026.
Abstract
{Gaussian} graphical models, estimated via precision matrices, are popular for uncovering underlying conditional dependencies among variables, yet the case of multimodal data with blockwise missing remains unaddressed. We propose a novel method, Direct Sparse Graphical Learning for Multimodal Data ({DSGL}), to handle this issue using only observed data. The {DSGL} consists of two stages: constructing a pilot estimator for the covariance matrix without imputation as an admissible input for {GLASSO}; and estimating the {DSGL} precision matrix via {GLASSO} with repeated cross-validation tuning. We further propose a thresholded variant to address false-positive edges, a common issue in high-dimensional data. We establish theoretical properties for {DSGL} with respect to element-wise deviation and its ability to recover the true graphical structure. In simulations and an Alzheimer’s Disease Neuroimaging Initiative ({ADNI}) application, {DSGL} outperforms imputation-based and other competing approaches, yielding more accurate graph estimation and lower Frobenius-norm error.