#### Glasnik Matematicki, Vol. 38, No.1 (2003), 111-120.

### A NOTE ON QUASI-ISOMETRIES II

### S. M. Patel

Department of Mathematics, Sardar Patel University,
Vallabh Vidyanagar, Gujarat, India

**Abstract.** An operator *A* on a complex Hilbert space *H*
is called a quasi-isometry if *A**^{2} *A*^{2} =
*A** *A*. In the present article,
some structural properties of quasi-isometries are established
with the help of operator matrix representation.

**2000 Mathematics Subject Classification.**
47A62, 47A63, 47B20.

**Key words and phrases.** Hilbert space, isometry, spectrum, operator matrix.

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