Hyperparameters are rarely independent. Changing one often forces another to change too —
the classic example is the linear scaling rule: as mini-batch size grows,
the learning rate should grow with it (roughly proportionally, or with a batchα power
law) to keep training stable. This scene renders a small search landscape over
log(learning rate) and log(batch size). A curved corridor —
the coupling constraint — is carved through the terrain in violet; configurations far from
that corridor are treated as infeasible and shaded red.
ln(batch) ≈ base + α · ln(lr). Points near it satisfy the LR–batch-size relationship.Tools like Optuna and Ray Tune let you encode exactly this kind of dependency — conditional search spaces where one hyperparameter's valid range depends on another's value — so the optimizer never wastes trials on combinations that were never going to work.
A 3D search landscape over learning rate and batch size, cut by a curved coupling constraint and an optional regularization-budget band, showing exactly how joint hyperparameter relationships shrink the feasible region an optimizer can search.
The violet corridor traces the ideal learning-rate/batch-size coupling (a generalized linear scaling rule). Configurations far from it — or that miss a second regularization-budget constraint — are shaded red as infeasible, mirroring how conditional search spaces work in tools like Optuna.
Adjust the coupling exponent and tolerance to bend and widen the feasible corridor, toggle the regularization constraint to see the feasible region shrink further, and resample random configurations to watch which ones pass both constraints.
Ignoring hyperparameter dependencies wastes enormous compute: a random search that doesn't know learning rate should scale with batch size will spend most of its trials on combinations that were never going to converge.