arXiv subjects

Cong Yang

Publications and source records attributed to Cong Yang.

3 recordsLinked to original sources

arXiv2026

Evolutionary Soups: Evolving Mixture-of-Experts for Multi-Objective LLM Alignment

Large language models are increasingly required to generate responses that satisfy multiple competing objectives. Since optimal trade-offs depend on both user preferences and input prompts, controllable multi-objective generation must dynamically adapt models at inference time without retraining. To address this, we propose Evolutionary Soups, a mixture-of-experts framework for fine-grained generation control, with gating networks trained via an evolutionary algorithm. The per-layer gating networks dynamically produce expert-merging coefficients from hidden-state representations, while the evolutionary algorithm incorporates greedy hypervolume contribution for effective evolution of these gating networks, achieving consistent improvements on large and noisy training datasets and broader coverage of the non-convex Pareto front. Experiments across three tasks demonstrate the effectiveness of Evolutionary Soups over baselines: it achieves the best hypervolume, linear utility, and Tchebyshev utility (~20% improvement) among controllable methods on all tasks.

cs.CL↗

arXiv2026

Federated Trust for Embodied Robot Capability Marketplaces

Robot capability marketplaces, the "app store for robot skills," are emerging as the deployment vector for LLM-driven robot fleets. The default cloud-native answer to "is this package safe to install?" is centralised PKI: one certificate authority, one transparency log, one root of trust. We argue this is the wrong model for embodied robot fleets, where operators face heterogeneous regulatory regimes, air-gapped deployments, tiny operator headcounts, and physical-world consequences for trusting the wrong publisher. We present federated trust: each deployed bridge maintains its own local trust directory of acceptable signers; signers identify themselves with a public key embedded in a detached Ed25519 signature envelope; install-time verification is a local set-membership check rather than a network round trip to a certificate authority. The cryptographic primitives are deliberately standard (Ed25519 detached signatures and SSH-style trust files); the contribution is the architectural commitment that this composition fits embodied robot fleets specifically. We implement the model in a runtime governance layer with a five-subcommand CLI, a registry server, a per-bridge install gate, and 80 tests. A multi-deployment evaluation shows the same registry stream producing divergent install verdicts on bridges with different trust directories, the load-bearing design property. Across 5000 adversarial trials, the strict-mode gate rejects 100% of rogue-publisher, tampered, forged, and revoked-signer attacks, and 96.6% of downgrade attempts under a minimum-version pin extension. A same-hardware comparison against Sigstore-Cosign and python-TUF locates federated trust's per-verify cost between the two and its per-publisher storage footprint below both.

cs.CR↗

arXiv2026

Audit-First Rollback Semantics for Safety-Critical Deployment Pipelines

Distributed deployment runtimes carry a coherence obligation that classical fault-tolerance frameworks do not name directly: the live state a component is configured to run and the audit chain that records how it got there must agree at every terminal configuration. Prior works mainly focus on individual aspects of the deploy-time fault surface (canary controllers, configuration rollback, signed attestations), leaving the cross-cutting question of audit/live coherence under fail-stop crash only loosely specified. Yet a key systems question remains unresolved: how can a deployment runtime guarantee that the audit chain answers truthfully about live state even when a transition crashes mid-flight? We present audit-first rollback semantics, a fault-tolerance mechanism that guarantees audit/live coherence at every committed terminal under fail-stop crashes during transition phases. The mechanism pairs with provisional state machines, pipelines whose "active but not yet promoted" states carry an explicit rollback contract and a bounded deadline. We instantiate both in a runtime deployment system and run a dependability evaluation against a fail-open variant of the same pipeline across twelve fault-injection points spanning three structural failure classes. Across 1,200 injected-failure trials, audit-first rollback achieves 100% audit/live-state coherence (600/600, Wilson 95% CI [0.994,1.000]) with per-cell p95 recovery latency below 500 ms (SLO PASS in 12/12 cells); the fail-open variant preserves coherence on only 33% of trials (200/600, Wilson 95% CI [0.297,0.372]). We further lift the construction to a cross-bridge coordination protocol with a safety argument for fleets of fail-stop bridges, leaving fleet-scale empirical evaluation to follow-on work.

cs.SE↗