arXiv subjects

Om Shastri

Publications and source records attributed to Om Shastri.

3 recordsLinked to original sources

arXiv2026

TimeSeek: Temporal Reliability of Agentic Forecasters

We introduce TimeSeek, a benchmark for studying how the reliability of agentic LLM forecasters changes over a prediction market's lifecycle. We evaluate 10 frontier models on 150 CFTC-regulated Kalshi binary markets at five temporal checkpoints, with and without web search, for 15,000 forecasts total. Models are most competitive early in a market's life and on high-uncertainty markets, but much less competitive near resolution and on strong-consensus markets. Web search improves pooled Brier Skill Score (BSS) for every model overall, yet hurts in 12% of model-checkpoint pairs, indicating that retrieval is helpful on average but not uniformly so. Simple two-model ensembles reduce error without surpassing the market overall. These descriptive results motivate time-aware evaluation and selective-deference policies rather than a single market snapshot or a uniform tool-use setting.

cs.AI↗

arXiv2026

Factor Dimensionality and the Bias-Variance Tradeoff in Diffusion Portfolio Models

In this paper, we implement and evaluate a conditional diffusion model for asset return prediction and portfolio construction on large-scale equity data. Our method models the full distribution of future returns conditioned on firm characteristics (i.e.\ factors), using the resulting conditional moments to construct portfolios. We observe a clear bias--variance tradeoff: models conditioned on too few factors underfit and produce overly diversified portfolios, while models conditioned on too many factors overfit, resulting in unstable and highly concentrated allocations with poor out-of-sample performance. Through an ablation over factor dimensionality, we reveal an intermediate number of factors that achieves the best generalization and outperforms baseline portfolio strategies.

cs.CE↗

arXiv2023

PICSARR: high-precision polarimetry using CMOS image sensors

We have built and tested a compact, low-cost, but very-high-performance astronomical polarimeter based on a continuously rotating half-wave plate and a high-speed imaging detector. The polarimeter is suitable for small telescopes up to ~1 m in aperture. The optical system provides very high transmission over a wide wavelength range from the atmospheric UV cutoff to ~1000 nm. The high-quantum-efficiency, low-noise and high-speed of the detectors enable bright stars to be observed with high-precision as well as polarization imaging of extended sources. We have measured the performance of the instrument on 20 cm and 60 cm aperture telescopes. We show some examples of the type of science possible with this instrument. The polarimeter is particularly suited to studies of the wavelength dependence and time variability of the polarization of stars and planets.

astro-ph.IM↗