Synapse: Evolving Job-Person Fit with Explainable Two-phase Retrieval and LLM-guided Genetic Resume Optimization

arXiv cs.LG / 4/6/2026

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Key Points

  • Synapse is presented as a multi-stage recruitment recommender that splits the workflow into high-recall candidate generation and high-precision semantic reranking to better match job requirements at scale and under cost constraints.
  • The system uses dense retrieval with FAISS plus an ensemble approach based on contrastive learning and LLM reasoning, improving recommendation ranking quality substantially over embedding-only baselines (nDCG@10 up by 22%).
  • To address transparency needs, Synapse adds a retrieval-augmented explanation layer that grounds recommendations in explicit evidence from retrieved materials.
  • It also introduces an “evolutionary resume optimization” method that refines candidate representations as a black-box optimization problem using Differential Evolution with LLM-guided mutation operators, achieving monotonic gains in recommender scores (over 60% relative in evaluated profiles) without labeled data.
  • The authors indicate they plan to release code and data after publication, suggesting practical adoption potential for the research pipeline.

Abstract

Modern recruitment platforms operate under severe information imbalance: job seekers must search over massive, rapidly changing collections of postings, while employers are overwhelmed by high-volume, low-relevance applicant pools. Existing recruitment recommender systems typically rely on keyword matching or single-stage semantic retrieval, which struggle to capture fine-grained alignment between candidate experience and job requirements under real-world scale and cost constraints. We present Synapse, a multi-stage semantic recruitment system that separates high-recall candidate generation from high-precision semantic reranking, combining efficient dense retrieval using FAISS with an ensemble of contrastive learning and Large Language Model (LLM) reasoning. To improve transparency, Synapse incorporates a retrieval-augmented explanation layer that grounds recommendations in explicit evidence. Beyond retrieval, we introduce a novel evolutionary resume optimization framework that treats resume refinement as a black-box optimization problem. Using Differential Evolution with LLM-guided mutation operators, the system iteratively modifies candidate representations to improve alignment with screening objectives, without any labeled data. Evaluation shows that the proposed ensemble improves nDCG@10 by 22% over embedding-only retrieval baselines, while the evolutionary optimization loop consistently yields monotonic improvements in recommender scores, exceeding 60% relative gain across evaluated profiles. We plan to release code and data upon publication.