ArrowSpace: Spectral Search For Embeddings and Graph Analysis

Paper

Abstract

ArrowSpace is a library that implements a novel spectral indexing approach for vector similarity search, combining traditional semantic similarity with graph-based spectral properties. The library introduces taumode (λτ , lambda-tau) indexing, which blends Rayleigh quotient smoothness energy from graph Laplacians with edge-wise dispersion statistics to create bounded, comparable spectral scores. This enables similarity search that considers both semantic content and spectral characteristics of high-dimensional vector datasets.

Briefly

Existing vector database solutions are not fine-tuned to the domain they apply to, current solutions mostly target word embeddings and use standard distance metrics (L2 distance/Euclidean, cosine and similar) or use (not very much cost-effective compared to the quality of the outcome) hashing functions. Spectral indexing allows fine-tuning vector search to the spectral signature of the domain the dataset belongs to, this enables finding associations of vectors that are not spotted by existing solutions (there is an example called `compare_cosine` in the repository). Imagine having an LLM that can find contexts that are related but not spotted by the same LLM using a traditional search, this means the possibility of discovering alternative patterns for the same problem-solving activity or even finding previously ignored meaningful connections. This comes with a simplification of the stack, one index can synthesise the spectrum of the vector; this gives advantages in index maintenance, interpretability and explainability of the dataset. These characteristics makes spectral indexing the perfect fit for medium-large datasets that need domain-specific precision in search (reference example: proteins structure datasets, like the `proteins_lookup` example in the the repository). In more general terms, this approach can also help overcome the theoretical limitations of single-vector search as highlighted by this paper.

Read the paper PDF.

Cite as: Lorenzo Moriondo. ArrowSpace: Spectral Indexing of Embeddings using taumode (λτ). August 28, 2025.
DOI: [To be assigned]

Implementation

Explore ArrowSpace for spectral vector search.
Unlock powerful spectral search for your vector space.