Direct Inference on Admissible Sets (Diona)
Abstract
We propose a new regression method named Direct Inference on Admissible Sets (Diona) that directly uses samples to estimate the state and its derivatives at a query point, along with their admissible bounds, without long global training. By casting the values and derivatives at the query and neighbouring samples as latent variables in a constrained optimisation problem, the burden of long training loops becomes one of on-demand local solves. We establish Diona's theoretical properties including finite-sample coverage and, in the noiseless case, convergence to the true state and derivatives under dense sampling. In a nonlinear regression benchmark on six functions of three to eight dimensions, Diona was more accurate than a Gaussian process (GP) on noiseless data especially with denser data sets. Furthermore, as with GP, it produced uncertainty bounds that contained the true value at more than 95% of query points in four functions. Diona's time to a first prediction after a data set update was three to four orders of magnitude shorter than that of the GP, and two to three orders shorter than that of a neural network, which was more accurate but offers no uncertainty quantification. This low latency is paid for by on-demand predictions, so this latency advantage applies when relatively few predictions are needed between data updates.
Figures & tables
| Name | Details |
|---|---|
| Neural network (NN) [ 1 ] | Implemented with Lux.jl . Fully connected network with hidden layers (64 tanh units). Trained to minimise MSE with Adam (25000 epochs with learning rate of ). Used CUDA via LuxCUDA.jl . |
| Gaussian process (GP) [ 11 ] | Sparse variational GP using AbstractGPs.jl , ApproximateGPs.jl , and KernelFunctions.jl , Matérn-5/2 kernel, and inducing points. |
| Nonlinear set membership (NSM) [ 8 ] | Implemented in Julia with estimated noise bound and value Lipschitz constant computed as in [ 10 ] . is then scaled by 2.5. |
| Radial basis functions (RBF) [ 2 ] | Using Surrogates.jl RadialBasis with the default linear radial kernel, with all default values. |
| Inverse distance weighting (IDW) | Using Surrogates.jl InverseDistanceSurrogate , using all training samples. Used inverse-distance exponent , otherwise all default settings. |
| Diona (ours) | As described in Section 4 - 5 , and with scaled by 2.5. LPs are computed with HiGHS.jl . |
| Function name | Domain | Properties | |
|---|---|---|---|
| Ishigami | 3 | Oscillatory, with growing amplitude, variable interactions | |
| Park | 4 | Nonseparable, spatially varying curvature | |
| Friedman | 5 | Nonlinear, nonseparable, with linear and quadratic additive terms | |
| Hartmann | 6 | Multimodal | |
| Piston (simulation) | 7 | (see [ 14 ] ) | Nonlinear physical model, input variable coupling |
| Rosenbrock | 8 | Narrow curved valley, strong input coupling |
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