Row-Hamiltonian Latin squares and Falconer varieties
A Latin square is a matrix of symbols such that each symbol occurs
exactly once in each row and column. A Latin square L is
row-Hamiltonian if the permutation induced by each pair of distinct
rows of L is a full cycle permutation. Row-Hamiltonian Latin squares
are equivalent to perfect 1-factorisations of complete bipartite
graphs. For the first time, we exhibit a family of Latin squares that
are row-Hamiltonian and also achieve precisely one of the related
properties of being column-Hamiltonian or symbol-Hamiltonian. This
family allows us to construct non-trivial, anti-associative,
isotopically L-closed loop varieties, solving an open problem posed by
Falconer in 1970.