LIME Τοπικές Επεξηγήσεις

LIME, short for Local Interpretable Model-agnostic Explanations, is a method for approximating a complex model around one example with a simpler explanation model. The original work describes a model-agnostic approach: it can query a classifier without needing access to its internal architecture. A user chooses an interpretable representation, such as presence or absence of words for text or segments for an image. To explain an instance, LIME creates perturbed versions in that interpretable representation, maps them back into inputs the original model can score, and gives more weight to perturbations considered close to the instance. It then fits a simple model, often a sparse linear model, to approximate the original model's outputs in that neighborhood. The resulting coefficients or selected conditions provide a compact local account. This approximation is not a global summary. A feature that matters near one example may matter differently elsewhere, and a single local surrogate may not capture a highly irregular decision surface. The explanation also depends on design choices: how inputs are perturbed, how distance is defined, how many samples are drawn, which features are allowed, and how the surrogate is regularized. In text, independent word removal can produce unnatural sentences; in images, segment boundaries influence which regions appear important. A plausible explanation is not automatically faithful. Check the surrogate's fit around the instance, repeat the explanation under reasonable settings, and test whether changing the highlighted features changes the original model as expected. Use a suitable domain representation and inspect whether perturbed examples remain meaningful. Compare with other evidence, such as counterfactual tests or global inspection, when decisions have consequences. LIME explains the behavior of a model around a selected input, not why the real-world outcome occurred. It does not establish causation, fairness, or correctness. Treat its output as a diagnostic aid, disclose its assumptions, and ensure a human reviewer can challenge the explanation rather than accepting a visually clear chart as proof.