  Within the framework of Becchi-Rouet-Stora-Tyutin (BRST) formalism, we
discuss some novel features of a two (1+1)-dimensional (2D) non-Abelian 1-form
gauge theory (without any interaction with matter fields). Besides the usual
off-shell nilpotent and absolutely anticommutating (anti-)BRST symmetry
transformations, we discuss the off-shell nilpotent and absolutely
anticommutating (anti-)co-BRST symmetry transformations. Particularly, we lay
emphasis on the existence of the coupled (but equivalent) Lagrangian densities
of the 2D non-Abelian theory in view of the presence of (anti-)co-BRST symmetry
transformations where we pin-point some novel features associated with the
Curci-Ferrari (CF) type restrictions. We demonstrate that these CF-type
restrictions can be incorporated into the (anti-)co-BRST invariant Lagrangian
densities through the fermionic Lagrange multipliers which carry specific ghost
numbers. The modified versions of the Lagrangian densities (where we get rid of
the new CF-type restrictions) respect some precise symmetries as well as a
couple of symmetries with CF-type constraints. These observations are
completely novel as far as the BRST formalism, with proper (anti-)co-BRST
symmetries, is concerned.
