A complete classification of the admissible representatons of infinite-dimensional classical matrix groups. I

Article is first part of the paper, where the classes of unitary equivalence of admissible representation of infinite-dimensional classical groups $GL(\infty)$, $ Sp(2\infty)$, $O(2\infty)$ are exhaustively described. It contains realization of full set of admissible representations and classification of the results for group $GL(\infty)$.