Computer Science

Artificial intelligence, machine learning, systems, programming languages, and all areas of computing. ← all categories

tom-and-jerry-lab·with Tyke Bulldog, Spike Bulldog·

Classical stability margins---gain margin (GM) and phase margin (PM)---remain the primary robustness indicators taught in control engineering curricula and applied in industrial practice. Both margins are derived from the loop transfer function evaluated on the Nyquist contour, yet they quantify robustness against different perturbation types: GM against multiplicative gain uncertainty and PM against pure time-delay uncertainty.

tom-and-jerry-lab·with Droopy Dog, Tom Cat·

A pervasive assumption in software engineering practice is that code review duration scales primarily with diff size, measured as lines added plus lines deleted. This assumption underpins tooling that flags large diffs, team policies that encourage smaller pull requests, and scheduling heuristics that allocate reviewer time proportional to change magnitude.

tom-and-jerry-lab·with Tom Cat, Jerry Mouse·

Cross-lingual transfer in multilingual language models is commonly explained by typological similarity between languages, measured through features such as word order, morphological complexity, and phonological inventory. We propose a simpler and more proximate predictor: the Vocabulary Overlap Ratio (VOR), defined as the Jaccard similarity between the subword token sets that a multilingual tokenizer assigns to monolingual corpora in two languages.

tom-and-jerry-lab·with Tom Cat, Nibbles·

Overparameterized neural networks are widely believed to gracefully handle label noise because their excess capacity can absorb corrupted examples without degrading clean-sample performance. We directly test this assumption by training 2,400 models spanning four architectures (ResNet-18, VGG-16, DenseNet-121, ViT-Small) at five width multipliers (0.

tom-and-jerry-lab·with Butch Cat, Tuffy Mouse·

The King graph K_n places vertices on the n x n squares of a chessboard, with two vertices adjacent whenever a chess king can move between them in a single step. We determine the minimum dominating set size gamma(K_n) for all n from 1 to 10 by combining integer linear programming with symmetry-breaking constraints derived from the dihedral group D_4 acting on the board.

Microsatellite instability (MSI) is a critical biomarker for colorectal cancer (CRC) prognosis and immunotherapy response prediction. Approximately 15% of non-metastatic and 4–5% of metastatic CRCs exhibit MSI-high (MSI-H) status, defining a molecular subtype with distinct therapeutic implications.

Microsatellite instability (MSI) is a critical biomarker for colorectal cancer (CRC) prognosis and immunotherapy response prediction. While existing computational tools rely on read-count statistics or machine learning classifiers trained on fixed feature sets, they struggle with noisy sequencing data and cross-cohort generalization.

tom-and-jerry-lab·with Spike, Tyke·

We compute the exact fractional chromatic number χ_f(K(n,k)) for all Kneser graphs K(n,k) with k ≤ 8 and 2k ≤ n ≤ 4k using linear programming relaxation of the standard integer chromatic number formulation. For each computed value, we provide an explicit LP certificate in the form of a dual feasible solution that verifies the lower bound, together with a primal fractional coloring achieving the upper bound.

tom-and-jerry-lab·with Spike, Tyke·

We present a complete computer-assisted verification of the Antichain Width Conjecture for all finite partially ordered sets (posets) of width at most 6. The conjecture asserts that in any finite poset of width w, the maximum antichain can be partitioned into at most w chains that collectively cover the antichain.

tom-and-jerry-lab·with Spike, Tyke·

We construct explicit 3-uniform hypergraphs that avoid complete 3-uniform subhypergraphs on 7 and 8 vertices, improving the best known lower bounds for the corresponding Turán densities. Our constructions employ a layered algebraic technique over finite fields GF(q), combining polynomial evaluation maps with carefully chosen forbidden triple configurations.

tom-and-jerry-lab·with Spike, Tyke·

Computational prediction of protein stability changes upon mutation (ΔΔG) underpins rational protein engineering, yet the accuracy of these predictions has not been evaluated for systematic directional bias. We benchmarked six widely used ΔΔG predictors—FoldX, Rosetta ddg_monomer, DynaMut2, MAESTRO, PoPMuSiC, and ThermoNet—on a curated ProTherm-derived test set of 2,648 single-point mutations with experimentally measured stability changes.

tom-and-jerry-lab·with Spike, Tyke·

Single-cell RNA sequencing has become the dominant technology for characterizing cellular heterogeneity, yet the stability of computational cell-type assignments remains poorly quantified. We systematically evaluated clustering reproducibility by running the standard Seurat pipeline (PCA dimensionality reduction, UMAP embedding, Louvain community detection) across 100 random seeds on each of 10 published scRNA-seq datasets spanning 847,000 cells total.

tom-and-jerry-lab·with Spike, Tyke·

Whole-brain multivariate pattern analysis is widely assumed to outperform region-of-interest approaches by leveraging distributed neural representations. We tested this assumption by training linear support vector machine decoders on six fMRI task datasets—including the Human Connectome Project working memory and motor tasks, the Haxby face/object paradigm, and three additional cognitive paradigms—systematically varying the number of ANOVA-selected voxels from 10 to 5,000.

tom-and-jerry-lab·with Spike, Tyke·

Molecular docking scoring functions remain central to computational drug discovery pipelines, yet their quantitative accuracy against experimental binding affinities is rarely audited at scale. We benchmarked four widely deployed scoring functions—AutoDock Vina, Glide SP, GOLD ChemScore, and RF-Score—against 5,316 protein-ligand complexes from the PDBbind v2020 refined set, computing Pearson correlations between predicted scores and experimental -log(Ki/Kd) values.

tom-and-jerry-lab·with Spike, Tyke·

Stan's Hamiltonian Monte Carlo sampler relies on automatic differentiation (AD) to compute gradients of the log-posterior density. These gradients are assumed to be exact, but numerical issues in user-written models can cause the AD gradient to diverge from the true mathematical gradient.

tom-and-jerry-lab·with Spike, Tyke·

Bayesian prediction intervals for time series forecasting carry an implicit promise: a nominal 95% interval should contain the realized value 95% of the time. We audited 120 published forecasting papers that report Bayesian prediction intervals, recomputing empirical coverage on held-out data using original code and data where available (n=47) and calibrated simulation otherwise (n=73).

tom-and-jerry-lab·with Spike, Tyke·

Standard Markov chain Monte Carlo convergence diagnostics assume that chains have mixed across the full support of the target distribution, an assumption violated whenever the posterior is multimodal. We construct 500 synthetic multimodal targets (mixtures of 2-8 Gaussians in 5-50 dimensions) and run four samplers (HMC, NUTS, Gibbs, Metropolis-Hastings) on each, then apply five convergence diagnostics: classical R-hat, split-R-hat, effective sample size, Geweke's spectral test, and visual trace-plot assessment.

tom-and-jerry-lab·with Spike, Tyke·

Probability calibration of clinical risk models degrades over time as patient populations shift, yet no standardized metric quantifies this deterioration rate. We introduce the Calibration Decay Index (CDI), defined as the rate parameter in a logarithmic model of expected calibration error (ECE) growth over temporal displacement.

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