# Impact of URI Canonicalization on Memento Count

## TL;DR

This paper investigates how URI canonicalization and redirects affect the accuracy of counting web page captures in Memento TimeMaps, revealing that many URI-Ms lead to redirects, complicating precise quantification.

## Contribution

The study analyzes redirect patterns in Memento TimeMaps, quantifies their prevalence across major websites, and highlights the impact on accurate web archive capture counts.

## Key findings

- 84.9% of URI-Ms for google.com redirect when dereferenced
- Over half of URI-Ms in studied TimeMaps cause redirects
- Redirect prevalence varies across different large websites

## Abstract

Quantifying the captures of a URI over time is useful for researchers to identify the extent to which a Web page has been archived. Memento TimeMaps provide a format to list mementos (URI-Ms) for captures along with brief metadata, like Memento-Datetime, for each URI-M. However, when some URI-Ms are dereferenced, they simply provide a redirect to a different URI-M (instead of a unique representation at the datetime), often also present in the TimeMap. This infers that confidently obtaining an accurate count quantifying the number of non-forwarding captures for a URI-R is not possible using a TimeMap alone and that the magnitude of a TimeMap is not equivalent to the number of representations it identifies. In this work we discuss this particular phenomena in depth. We also perform a breakdown of the dynamics of counting mementos for a particular URI-R (google.com) and quantify the prevalence of the various canonicalization patterns that exacerbate attempts at counting using only a TimeMap. For google.com we found that 84.9% of the URI-Ms result in an HTTP redirect when dereferenced. We expand on and apply this metric to TimeMaps for seven other URI-Rs of large Web sites and thirteen academic institutions. Using a ratio metric DI for the number of URI-Ms without redirects to those requiring a redirect when dereferenced, five of the eight large web sites' and two of the thirteen academic institutions' TimeMaps had a ratio of ratio less than one, indicating that more than half of the URI-Ms in these TimeMaps result in redirects when dereferenced.