---
license: apache-2.0
language:
- en
tags:
- rag
- retrieval
- semantic-search
- faiss
- bm25
- cross-encoder
- sentence-transformers
- hybrid-search
- dense-retrieval
- ai
- search
pipeline_tag: sentence-similarity
library_name: sentence-transformers
---
# ApexRetriever

A lightweight hybrid retrieval system designed for fast semantic search and RAG pipelines.

Built for:
- semantic search
- lightweight RAG
- AI assistants
- retrieval systems
- local document QA

---

# Architecture

## Stage ① — BM25 Sparse Retrieval
Keyword-based retrieval for fast lexical matching.

## Stage ② — Dense Semantic Search
Powered by:

- `BAAI/bge-small-en-v1.5`

Uses FAISS vector indexing.

## Stage ③ — CrossEncoder Reranking
Final neural reranking using:

- `cross-encoder/ms-marco-MiniLM-L-6-v2`

---

# Features

- Hybrid retrieval
- Fast indexing
- Dense semantic search
- Neural reranking
- Lightweight deployment
- GPU acceleration
- FAISS support
- Easy integration

---

# Repository Structure

```text
ApexRetriever/
│
├── bi_encoder/
├── reranker/
├── pipeline.py
└── README.md
````

---

# Installation

```bash
pip install -U \
    sentence-transformers \
    transformers \
    faiss-cpu \
    rank-bm25 \
    torch
```

---

# Quick Start

```python
from pipeline import ApexRetriever

retriever = ApexRetriever(model_dir=".")

# Example documents

docs = [
    "Python was created by Guido van Rossum.",
    "Paris is the capital of France."
]

retriever.index_documents(docs)

results = retriever.retrieve(
    "Who created Python?",
    top_k=3
)

print(results)
```

---

# Use Cases

* RAG systems
* Semantic search
* AI chatbots
* Knowledge retrieval
* Local search engines
* Memory systems

---

# Performance

Recommended:

* CUDA GPU
* 8GB+ RAM
* Python 3.10+

---

# Components

| Component     | Model                                |
| ------------- | ------------------------------------ |
| Dense Encoder | BAAI/bge-small-en-v1.5               |
| Reranker      | cross-encoder/ms-marco-MiniLM-L-6-v2 |
| Vector Engine | FAISS                                |
| Sparse Search | BM25                                 |

---

# License

Apache 2.0

---
> QuantaSparkLabs