전인호
20180502T08:15:38Z
20180502T08:15:38Z
2004
0378620X
OAK2215
http://dspace.ewha.ac.kr/handle/2015.oak/242754
Let B (H) denote the algebra of operators on a complex Hilbert space H, and let u denote the class of operators A ∈ B(H) which satisfy the absolute value condition
A
2 ≤
A2
. It is proved that if A ∈ u is a contraction, then either A has a nontrivial invariant subspace or A is a proper contraction and the nonnegative operator D =

2 is strongly stable. A PutnamFuglede type commutativity theorem is proved for contractions A in U, and it is shown that if normal subspaces of A ∈ U are reducing, then every compact operator in the intersection of the weak closure of the range of the derivation δA(X) = AX  XA with the commutant of A* is quasinilpotent.
English
Contractions satisfying the absolute value property
A
2 ≤
A2
Article
2
49
SCI
SCIE
SCOPUS
141
148
Integral Equations and Operator Theory
10.1007/s000200021202z
WOS:000222028700001
2s2.02942616536
Duggal B.P.
Jeon I.H.
Kubrusly C.S.
20180501154355