Tag
decision-trees
- Jun 16, 2026 Cost-Complexity Pruning and the Weakest-Link Sequence How a maximal tree is collapsed into a nested family of subtrees indexed by one penalty parameter, and why the sequence makes cross-validation cheap. machine learning
- May 31, 2026 Pattern Matching and the Exhaustiveness Check How a match expression is compiled into a decision tree, why exhaustiveness is decidable for constructors but not for guards, and what an unreachable arm costs. programming languages
- Feb 2, 2026 The Comparison Sorting Lower Bound and What It Actually Counts Why comparison sorts need about n log n comparisons, how the decision-tree and adversary arguments differ, and which cost models the bound leaves out. algorithms
- Jan 17, 2026 Comparison Lower Bounds From Decision Trees and Adversaries Counting distinguishable outcomes gives the n log n sorting bound. When that counting is not available, an adversary argument supplies the same conclusion by a different route. algorithms
- Jan 6, 2026 How CART Scans Sorted Feature Values for the Best Split Threshold The greedy split search reduces to a single sorted pass per feature, with incremental class counts turning an apparent quadratic problem into a linear scan. machine learning
- Jul 10, 2024 Gini, Entropy, and Why Misclassification Error Cannot Grow a Tree Three impurity functions look interchangeable, but only the strictly concave ones produce a useful ranking of splits. A worked partition shows where the third fails. machine learning
- Nov 15, 2023 LambdaMART and Metric-Driven Gradient Boosting How lambda gradients weight document pairs by their effect on NDCG, why the resulting tree ensemble is trained on pseudo-residuals, and where the heuristic gradient fails. information retrieval