  We give an action of the symmetric group on non-commuting indeterminates in
terms of series in the corresponding Mal'cev-Newmann division ring. The action
is constructed from the non-Abelian Hirota-Miwa (discrete KP) system. The
corresponding companion map, which gives generators of the action, is discussed
in the generic case and the corresponding explicit formulas have been found in
the periodic reduction. We discuss also briefly connection of the companion to
the KP map with context-free languages.
