Given vectors 
and 
, let 
denote the class of (0,1)-matrices
with row sum vector 
and column sum vector 
. The interchange graph 
of 
has vertex set 
, with two matrices adjacent 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, a property they call maximally Hamiltonian.
