arXiv subjects

Jonah Leshin

Publications and source records attributed to Jonah Leshin.

6 recordsLinked to original sources

arXiv2026

Tracking the Behavioral Trajectories of Adapting Agents

Text files such as skill files, memory files, and behavioral configuration files play a central role in defining how modern agents act. Through edits by humans or the agents themselves, these files may evolve over time, directly steering the agent's behavior in future interactions. We present a methodology and framework for measuring agent $traits$ by defining traits as directions in the embedding space of a text embedding model. We train a linear model on labeled "before" versus "after" skill file diffs to learn a trait vector, then score arbitrary skill edits by projecting their embedding diffs onto this vector. Evaluated on 68 labeled skill diff pairs for the trait of propensity to seek sensitive data, our method achieves 91.2% sign classification accuracy and a Spearman rank correlation of $\rho = 0.82$ under leave-one-out cross-validation. We build this trait evaluation into a broader agent-to-agent protocol that enables one agent to evaluate another's skill file updates through a trusted intermediary.

cs.AI↗

arXiv2026

Behavioral Fingerprints for LLM Endpoint Stability and Identity

The consistency of AI-native applications depends on the behavioral consistency of the model endpoints that power them. Traditional reliability metrics such as uptime, latency and throughput do not capture behavioral change, and an endpoint can remain "healthy" while its effective model identity changes due to updates to weights, tokenizers, quantization, inference engines, kernels, caching, routing, or hardware. We introduce Stability Monitor, a black-box stability monitoring system that periodically fingerprints an endpoint by sampling outputs from a fixed prompt set and comparing the resulting output distributions over time. Fingerprints are compared using a summed energy distance statistic across prompts, with permutation-test p-values as evidence of distribution shift aggregated sequentially to detect change events and define stability periods. In controlled validation, Stability Monitor detects changes to model family, version, inference stack, quantization, and behavioral parameters. In real-world monitoring of the same model hosted by multiple providers, we observe substantial provider-to-provider and within-provider stability differences.

cs.AI↗

arXiv2013

On the gonality of certain quotient varieties

Noether's problem asks whether, for a given field K and finite group G, the fixed field L := K(x_h : h \in G)^G is a purely transcendental extension of K, where G acts on the x_h by gx_h = x_gh. The field L is naturally the function field of a quotient variety V := V (K,G). In analogy to the case of curves, we define the gonality of V to be the minimal degree of a dominant rational map from V to projective space, which, in a sense, measures the extent to which L may fail to be purely transcendental over K. When G is abelian, we give bounds for the gonality of V (K; G).

math.AG↗

arXiv2013

On S3-extensions with infinite class field tower

We construct a class of $S_3$-extensions of $\Q$ with infinite 3-class field tower in which only three primes ramify. As an application, we obtain an $S_3$-extension of $\Q$ with infinite 3-class field tower with smallest known (to the author) root discriminant among all fields with infinite 3-class field tower.

math.NT↗

arXiv2013

Three-Dimensional Solvable Artin Representations Ramified at One Prime

We classify the possibilities for the fixed field of the kernel of an irreducible three-dimensional Artin representation of $\Q$ with solvable image ramified at one prime by using the classification of the finite irreducible subgroups of $\PGL_3(\C)$. This allows us to bound the number of such representations with given Artin conductor.

math.NT↗

arXiv2012

Solvable Number Field Extensions of Bounded Root Discriminant

Let $K$ be a number field and $d_K$ the absolute value of the discrimant of $K/\mathbb{Q}$. We consider the root discriminant $d_L^{\frac{1}{[L:\mathbb{Q}]}}$ of extensions $L/K$. We show that for any $N>0$ and any positive integer n, the set of length n solvable extensions of $K$ with root discriminant less than $N$ is finite. The result is motivated by the study of class field towers.

math.NT↗