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New York Journal of Mathematics
Volume 32 (2026), 1287-1300

  

Monojit Bhattacharjee, Rajeev Gupta, and Vidhya Venugopal

Wold-type decomposition for doubly commuting two-isometries

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Published: August 25, 2026.
Keywords: m-isometry, m-concave operators, wandering subspace property, Wold-type decomposition, Dirichlet-type spaces.
Subject [2020]: Primary 46E20, 47B32, 47B38, Secondary 47A50, 31C25.

Abstract
In this article, we prove that any pair of doubly commuting 2-isometries on a Hilbert space has a Wold-type decomposition. Moreover, the analytic part of the pair is unitary equivalent to the pair of multiplication by the coordinate functions on a Dirichlet-type space on the bidisc.

Acknowledgements

The first named author's research is supported by the DST-INSPIRE Faculty Grant with Fellowship No. DST/INSPIRE/04/2020/001250 and the third named author's research work is supported by the BITS Pilani institute fellowship.


Author information

Monojit Bhattacharjee
Department of Mathematics
Birla Institute of Technology and Science
K K Birla Goa Campus, India

monojitb@goa.bits-pilani.ac.in

Rajeev Gupta
School of Mathematics and Computer Science
Indian Institute of Technology Goa, India

rajeev@iitgoa.ac.in

Vidhya Venugopal
Department of Mathematics
Birla Institute of Technology and Science
K K Birla Goa Campus, India

p20200024@goa.bits-pilani.ac.in