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The automorphism group of the set of 12 points associated with an apolar system of conics is determined. A complete (q -&arc for q = 13 can be obtained as a special case. The orbits of its automorphism group are also described. 0 I Y Y~ John Wile?. & Sons, h e .

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Since E. Wigner set up a framework of the relativistically covariant quantum mechanics, several aspects of unitary representations of the Poincaré group have been investigated (see [8], [16]). In this paper it will be shown that some unitary representations of the Poincaré group are irreducible, even if they are restricted to the Poincaré semigroup (Theorem 1, 2 and 3).

DIFFERENTIAL OPERATORS WITH SHORT RANGE POTENTIALS S. ITATSU AND H. KANETA §1. Introduction and main theoremThe purpose of the present paper is to give a complete proof of the theorem which will be used in a paper of the second author [4].We will discuss certain spectral properties of self adjoint ordinary differential operators of the form iA