The -matrix
interchange graph
for vectors
and
is the graph whose vertex set is
, where
is the class of (0,1)-matrices
with row sum vector
and column sum vector
, and in which two matrices in
are adjacent exactly when one is obtained from the other
by a single
interchange, i.e., by complementing all four entries of a checkerboard
submatrix (Baggett and
Yan 2026). This use of the term interchange graph is distinct from its older use
as a synonym for a line graph (van Rooij and Wilf 1965).
When ,
the vertices are permutation matrices and
is the complete transposition graph. Baggett
and Yan (2026) proved that
is H*-connected
whenever
is nonempty.