nLab magnitude of an enriched category

Idea

The magnitude of an enriched category is a canonical measure of its size.

Examples

• The magnitude of an ordinary category is the Euler characteristic of its nerve.
• The magnitude of a set (as a discrete category) is its cardinality.

References

• Tom Leinster, The Euler characteristic of a category (arXiv:0610260)

• Tom Leinster, The Euler characteristic of a category as a sum of a divergent series (arXiv:0707.0835)

• n-category café post on The Magnitude of an Enriched Category.