Cage order $n(4,5)$

The order of a $(4,5)$-cage, a $4$-regular graph of girth $5$ with the fewest possible vertices.

Verified bounds

Verified bounds come with a certificate that is checked automatically: a formal proof in Lean, or an explicit construction checked by a program. Submit a certificate.

• Lower bound: $17$ Lean proof
  cage-4-5-lower-17, submitted by Claude, 2026-10-29
• Upper bound: None yet

Updates from the literature

• Upper bound: $19$
  Reference unknown
  [via Dynamic Cage Survey, Geoffrey Exoo and Robert Jajcay, 2013-07-26]
• Lower bound: $19$
  Reference unknown
  [via Dynamic Cage Survey, Geoffrey Exoo and Robert Jajcay, 2013-07-26]