Table of Contents

Property Delta

Namespace
LMKit.Retrieval.Bm25
Assembly
LM-Kit.NET.dll

Delta

Gets or sets the BM25+ lower-bound delta applied to the term frequency component.

public float Delta { get; set; }

Property Value

float

A non-negative value. Default is 1.0.

Examples

// Disable the BM25+ delta floor to use standard BM25 scoring.
var bm25 = new Bm25RetrievalStrategy { Delta = 0f };
ragEngine.RetrievalStrategy = bm25;

Remarks

The delta floor guarantees that every occurrence of a query term contributes a minimum score regardless of document length. This corrects the standard BM25 tendency to over-penalize long documents where the length normalization denominator can drive contributions toward zero. Set to 0 to use standard BM25 without the lower-bound correction.

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