QUASIRECOGNIZABILITY OF SIMPLE UNITARY GROUPS OVER FIELDS OF EVEN ORDER
We refer to the set of element orders of a finite group as the spectrum of this group and say that two groups are isospectral if their spectra coincide. We prove that finite simple unitary groups of dimension at least 5 over fields of characteristic 2 other than <i>U</i>5(2) are quasirecognizable by spectrum, that is every finite group isospectral to such unitary group <i>U </i>has a unique nonabelian composition factor and this factor is isomorphic to <i>U</i>.