The length of the largest-sized square contained within the Ferrers diagram of a partition. Its size can be determined using DurfeeSquare[f] in the Wolfram Language package Combinatoricaˋ . The size of the Durfee square remains unchanged between a partition and its conjugate partition. In the plot above, the Durfee square has size 3.

conjugate partition | Durfee polynomial | Ferrers diagram | partition