  We study Hamiltonians with point interactions in spaces of vector-valued
functions. Using some information from the theory of quantum graphs we describe
a class of the operators which can be reduced to the direct sum of several
one-dimensional problems. It shown that such reduction is closely connected
with the invariance under channel permutations. Examples are provided by some
"model" interactions, in particular, the so-called delta, delta-prime, and the
Kirchhoff couplings.
