Y. Brihaye et al., IRREDUCIBLE REPRESENTATIONS OF AN ALGEBRA UNDERLYING HIDDEN SYMMETRIES OF A CLASS OF QUASI EXACTLY SOLVABLE SYSTEMS OF EQUATIONS, Communications in Mathematical Physics, 187(1), 1997, pp. 201-226
The set of linear, differential operators preserving the vector space
of couples of polynomials of degrees n and n - 2 in one real variable
leads to an abstract associative graded algebra A(2). The irreducible,
finite dimensional representations of this algebra are classified int
o five infinite discrete sets and one exceptional case. Their matrix e
lements are given explicitly. The results are related to the theory of
quasi exactly solvable equations.