Since question says "how many", and model is theoretical, report the exact calculation.

Tue, 05 May 2026 05:05:23 +0000

Title: How Many Theoretical Models of Information Retrieval Exist? A Precise Theoretical Calculation --- Introduction
When users ask “how many” in the context of information retrieval (IR), they often seek a definitive count. However, since information retrieval is a theoretical and evolving domain—encompassing diverse models, frameworks, and algorithmic paradigms—the precise number of distinct theoretical models hinges on how we define “model” and “information retrieval.” This article delivers a rigorous theoretical calculation, clarifying the scope and boundaries of existing theoretical models, and provides the exact count based on established classifications. ---