ZarankiewiczDB,

an online database of Zarankiewicz numbers.

z(23,25) = 121

By deleting 8 rows and 6 columns from the finite projective plane of order 5.

lower bound = 121, submitted on April 25th, 2016 (link)

Searching for matrices of weight greater than 121, all but 2 scaffolds were eliminated without search.

Scaffold: $p=4$, $q=5$, $\mathbf{m}=(4,4,4,4)$, $\mathbf{n}=(4,4,4,3,3)$, $m_O=3$, $n_O=0$.

(0.002413556 seconds, score = 0, 0 recursive calls, max depth = 0)

Scaffold: $p=4$, $q=5$, $\mathbf{m}=(4,4,4,4)$, $\mathbf{n}=(4,4,3,3,3)$, $m_O=3$, $n_O=1$.

(20239.183004089 seconds, score = 0, 157319031 recursive calls, max depth = 34)

upper bound = 121, submitted by Andrew Kay on April 25th, 2016 (link)

Submit a result or comment?