# Professor Marco Marletta

Head of Mathematical Analysis Group

- marlettam@cardiff.ac.uk
- +44 (0)29 2087 5552
- 5.52, Abacws, Senghennydd Road, Cathays, Cardiff, CF24 4AG

## Overview

My interests are in spectral problems for ordinary and partial differential operators and operator pencils, and involve both analysis and computational mathematics. The Engineering and Physical Sciences Research Council have funded my work since 1994 and I have also had significant funding from the Leverhulme Trust and the London Mathematical Society.

I work on spectral problems for ODEs and PDEs on infinite domains. Central to this have been the theory of boundary triples, Dirichlet to Neumann maps, esessential numerical ranges, and complex function theory. I also work on inverse problems in spectral theory: these involve determining a problem from a knowledge of its spectral properties, usually through the Dirichlet to Neumann map, and have numerous applications.

My most recent work has been on Maxwell equations.

In 2016 I was elected as a Fellow of the Learned Society of Wales.

I am a member of the London Mathematical Society, the European Mathematical Society and the Society for Industrial and Applied Mathematics.

I am a member of the Editorial Board of the LMS.

Please see my personal web page for further details.

### Research group

### Administrative duties

- Head of the Mathematical Analysis Group
- Member of School Research Committee

I was Deputy Head of School for 10 years and Director of Research for 8 years. These appointments ended on 30th of November 2021.

### Personal website

## Biography

## Publications

### 2022

- Ben-Artzi, J., Marletta, M. and Rosler, F. 2022. Universal algorithms for computing spectra of periodic operators. Numerische Mathematik 150, pp. 719-767. (10.1007/s00211-021-01265-w)
- Ben-Artzi, J., Marletta, M. and Rosler, F. 2022. Computing scattering resonances. Journal of the European Mathematical Society

### 2021

- Ben-Artzi, J., Marletta, M. and Rosler, F. 2021. Computing the sound of the sea in a seashell. Foundations of Computational Mathematics (10.1007/s10208-021-09509-9)
- Aljawi, S. and Marletta, M. 2021. On the eigenvalues of spectral gaps of matrix-valued Schrödinger operators. Numerical Algorithms 86, pp. 637-657. (10.1007/s11075-020-00904-x)

### 2020

- Bogli, S. and Marletta, M. 2020. Essential numerical ranges for linear operator pencils. IMA Journal of Numerical Analysis 40(4), pp. 2256-2308. (10.1093/imanum/drz049)
- Bogli, S., Marletta, M. and Tretter, C. 2020. The essential numerical range for unbounded linear operators. Journal of Functional Analysis 279(1), article number: 108509. (10.1016/j.jfa.2020.108509)
- Brown, B. M., Marletta, M., Naboko, S. and Wood, I. 2020. The functional model for maximal dissipative operators (translation form): an approach in the spirit of operator knots. Transactions of the American Mathematical Society 373, pp. 4145-4187. (10.1090/tran/8029)

### 2019

- Brown, B. M., Marletta, M., Naboko, S. and Wood, I. 2019. The detectable subspace for the Friedrichs model. Integral Equations and Operator Theory 91, article number: 49. (10.1007/s00020-019-2548-9)
- Alberti, G. S., Brown, M., Marletta, M. and Wood, I. 2019. Essential spectrum for Maxwell's equations. Annales Henri Poincaré 20, pp. 1471-1499. (10.1007/s00023-019-00762-x)

### 2017

- Drabek, P., Kuliev, K. and Marletta, M. 2017. Some criteria for discreteness of spectrum of half-linear fourth order Sturm-Liouville problem. Nonlinear Differential Equations and Applications NoDEA 24(2), article number: 11. (10.1007/s00030-017-0433-2)
- Brown, B. M., Marletta, M., Wood, I. and Naboko, S. 2017. Inverse problems for boundary triples with applications. Studia Mathematica 237(3), pp. 241-275. (10.4064/sm8613-11-2016)

### 2016

- Brown, M., Marletta, M. and Symons, F. 2016. Uniqueness from discrete data in an inverse spectral problem for a pencil of ordinary differential operators. Journal of the London Mathematical Society 94(3), pp. 793-813. (10.1112/jlms/jdw059)
- Brown, B. M., Marletta, M., Naboko, S. N. and Wood, I. G. 2016. Detectable subspaces and inverse problems for Hain-Lüst-type operators. Mathematische Nachrichten 289(17-18), pp. 2108-2132. (10.1002/mana.201500231)
- Brown, B. M., Marletta, M. and Reyes Gonzales, J. M. 2016. Uniqueness for an inverse problem in electromagnetism with partial data. Journal of Differential Equations 260(8), pp. 6525-6547. (10.1016/j.jde.2016.01.002)

### 2014

- Boegli, S., Brown, B. M., Marletta, M., Tretter, C., Tretter, C. and Wagenhoffer, M. 2014. Guaranteed resonance enclosures and exclosures for atoms and molecules. Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 470(2171), article number: 20140488. (10.1098/rspa.2014.0488)
- Marletta, M. and Naboko, S. 2014. The finite section method for dissipative operators. Mathematika 60(2), pp. 415-443. (10.1112/S0025579314000126)

### 2013

- Marletta, M. and Tretter, C. 2013. Spectral bounds and basis results for non-self-adjoint pencils, with an application to Hagen-Poiseuille flow. Journal of Functional Analysis 264(9), pp. 2136-2176. (10.1016/j.jfa.2013.02.008)

### 2012

- Boulton, L., Marletta, M. and Rule, D. 2012. On the Stability of a Forward-Backward Heat Equation. Integral Equations and Operator Theory 73(2), pp. 195-216. (10.1007/s00020-012-1963-y)
- Marletta, M. and Scheichl, R. 2012. Eigenvalues in spectral gaps of differential operators. Journal of Spectral Theory 2(3), pp. 293-320. (10.4171/JST/30)

### 2010

- Marletta, M. 2010. Neumann-Dirichlet maps and analysis of spectral pollution for non-self-adjoint elliptic PDEs with real essential spectrum. IMA Journal of Numerical Analysis 30(4), pp. 917-939. (10.1093/imanum/drp017)
- Brown, B. M., Langer, M., Marletta, M., Tretter, C. and Wagenhofer, M. 2010. Eigenvalue enclosures and exclosures for non-self-adjoint problems in hydrodynamics. LMS Journal of Computation and Mathematics 13, pp. 65-81. (10.1112/S1461157008000466)
- Marletta, M., Shterenberg, R. and Weikard, R. 2010. On the inverse resonance problem for Schrödinger operators. Communications in Mathematical Physics 295(2), pp. 465-484. (10.1007/s00220-009-0928-8)
- Hiscox, A. J., Brown, B. M. and Marletta, M. 2010. On the low energy behavior of Regge poles. Journal of Mathematical Physics 51(10), article number: 102104. (10.1063/1.3496811)

### 2009

- Marletta, M. and Rozenblum, G. 2009. A Laplace operator with boundary conditions singular at one point. Journal of Physics A: Mathematical and Theoretical 42(12), article number: 125204. (10.1088/1751-8113/42/12/125204)

### 2008

- Brown, B. M., Marletta, M., Naboko, S. and Wood, I. 2008. Boundary triplets and M-functions for non-selfadjoint operators, with applications to elliptic PDEs and block operator matrices. Journal of the London Mathematical Society 77(3), pp. 700-718. (10.1112/jlms/jdn006)

### 2007

- Marletta, M. and Tretter, C. 2007. Essential spectra of coupled systems of differential equations and applications in hydrodynamics. Journal of Differential Equations 243(1), pp. 36-69. (10.1016/j.jde.2007.09.002)

### 2005

- Marletta, M. and Weikard, R. 2005. Weak stability for an inverse Sturm-Liouville problem with finite spectral data and complex potential. Inverse problems 21(4), pp. 1275-1290. (10.1088/0266-5611/21/4/005)

### 2004

- Greenberg, L. and Marletta, M. 2004. The Ekman flow and related problems: spectral theory and numerical analysis. Mathematical Proceedings of the Cambridge Philosophical Society 136(3), pp. 719-764. (10.1017/S030500410300731X)
- Brown, B. M. and Marletta, M. 2004. Spectral inclusion and spectral exactness for PDEs on exterior domains. IMA Journal of Numerical Analysis 24(1), pp. 21-43. (10.1093/imanum/24.1.21)

### 2001

- Brown, B. M. and Marletta, M. 2001. Spectral inclusion and spectral exactness for singular non-self-adjoint Sturm-Liouville problems. Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 457(2005), pp. 117-139. (10.1098/rspa.2000.0659)

## Teaching

- Foundations I
- Mathematics Masterclass

### Current and past collaborators

- Lidia Aceto in University of Eastern Piemonte.
- Giovanni Alberti in Genova.
- Jonathan Ben-Artzi in Cardiff.
- Sabine Boegli in Durham.
- Malcolm Brown in the School of Computer Science in Cardiff.
- Des Evans in Cardiff.
- Francesco Ferraresso in Cardiff.
- Paolo Ghelardoni, Giovanni Gheri and Cecilia Magherini at Universita` di Pisa.
- Leon Greenberg at the University of Maryland at College Park, sadly deceased in September 2003.
- James Hinchcliffe, a trustee of the charity DEBRA.
- Lucas Jodar of Universitat Politecnica de Valencia.
- Ian Knowles of University of Alabama at Birmingham.
- Michael Levitin of University of Reading.
- Carsten Maple, now in Warwick. Carsten was my first PhD student and got a chair before I did.
- Sergei Naboko of Saint Petersburg State University, sadly deceased on 25th of December 2020.
- John Pryce of the School of Mathematics here in Cardiff, who was my PhD supervisor.
- Frank Roesler in Cardiff.
- Roman Romanov of Saint Petersburg State University.
- Andrei Shkalikov of Moscow State University.
- Christiane Tretter of the University of Bern.
- Matthias Langer of the University of Strathclyde
- Marcus Wagenhofer formerly of the University of Bremen.
- Anton Zettl of Northern Illinois University.
- Rudi Weikard of University of Alabama at Birmingham.
- Ian Wood in Kent.

### External funding since 2000

My research funding from EPSRC has been continuous since I obtained my first grant in 1994. I have also benefitted immensely from the sponsorship of the Leverhulme Trust, the London Mathematical Society, the Royal Society and the European Union, as well as from funding provided by ICMS in Edinburgh and INI in Cambridge.

- Principal Investigator, EPSRC PDRA grant on Spectral Localisation of Operator Pencils and Analytic Operator-Valued Functions: £324,844
- Joint Investigator, EPSRC Network on Mathematics of Inverse Problems: £99,578.
- Joint Investigator, EPSRC PDRA Grant on Inverse Problems in Magnetic Imaging: £430,833
- Principal Investigator, WIMCS-Leverhulme Fellowships on Dissipative Operator Theory (£160,977)
- Scientist in Charge, EU Marie Curie Project GRAPH-COUPL
- Principal Investigator, EPSRC PDRA grant, with B.M. Brown (2005)
- Sole applicant, EPSRC VF grant for Prof. C. Tretter (2004)
- Joint investigator, EPSRC VF grant for Prof. S.N. Naboko (2004)
- Leverhulme Fellowship (2001-2002)
- Principal investigator, EPSRC VF grant for Prof A.A. Shkalikov (2001)
- Sole applicant, EPSRC VF grant for Prof. L. Greenberg (2000)
- Sole applicant, EPSRC VF grant for Prof. L. Jodar (1998)
- Sole applicant, EPSRC VF grant for Prof. L. Greenberg (1998)
- Sole applicant, EPSRC VF grant for Prof. L. Greenberg (1996)
- Sole applicant, EPSRC VF grant for Prof. L. Greenberg (1994)
- Joint applicant, 1998 EPSRC Numerical Analysis Summer School
- Joint applicant, 1996 EPSRC Numerical Analysis Summer School
- Joint applicant, 1994 EPSRC Numerical Analysis Summer School
- Joint investigator, EPSRC PDRA grant, with B.M. Brown and W.D. Evans (2002)
- EPSRC postdoc grant GR/R20885/01 (2002 to 2005)
- EPSRC postdoc grant EP/C008324/1 (2006 to 2008)
- EPSRC VF grant GR/S74072/01 (2004 to 2006)
- EPSRC VF grant GR/S47229/01 (2004)
- Leverhulme Fellowship (2001 to 2002)
- EPSRC VF grant GR/R44959/01 (2001 to 2002)
- EPSRC VF grant GR/N26159/01 (2000 to 2001)

### Invited conference and workshop talks

- Plenary speaker, IWOTA, Krakow, 2022.
- Plenary speaker, Ricardo Wedder 70th birthday meeting, Mexico City, 2020.
- Plenary speaker, OTAMP, Euler Institute, St Petersburg, 2016.
- Plenary speaker, BIRS-Oaxaca meeting on Dirichlet to Neumann maps, 2016.
- Plenary speaker, Spectral Theory and Applications, Krakow, 2015.
- AIM Workshop on the Mathematical Aspects of Physics with Nonselfadjoint Operators, June 2015.
- Plenary speaker, Kent Spectral Theory Meeting, Canterbury, March 2014.
- Plenary speaker, TU-Hamburg ‘Kickoff Meeting’ on Applied Analysis, Hamburg-Harburg, July 2012.
- Bath-RAL NA Conference, September 2008.
- `Numerical Approaches to Oscillatory Functions', Ghent, January 2008.
- Banach Centre Spectral Theory Workshop, Warsaw, 2007; 2005; 2003.
- Inverse Problems Workshop, University of Liverpool, March 2006.
- Durham Symposium on Spectral Theory, 2005
- Banach Centre Conference on Operator Theory, Warsaw, Poland, July 2005.
- American Mathematical Society Meeting, Nashville, Tenessee, October 2004.
- AMS Meeting, Nashville, 2004.
- Operator Theory and Applications in Mathematical Physics', keynote speaker, Poland, 2004.
- EPSRC Spectral Theory Network, December 2003.
- Banach Centre Conference on Operator Theory, Warsaw, Poland, August 2003.
- EPSRC Spectral Theory Network, October 2001.
- Scottish Computational Mathematics Symposium, Edinburgh, 2001.
- Interdisciplinary Research Conference, Universitat Politecnica de Valencia, September 2001. Organizer: L. J`odar.
- Scottish Computational Mathematics Conference, September 2001. Organizer: D. Sloan.
- ‘Geometric Integration’: EPSRC-LMS workshop, Durham, July 2000.
- Course of seminars on Hamiltonian Systems at the University of Pisa, April 1999.
- ‘Computational Spectral Theory’: EPSRC workshop (1996).
- ‘Computational Spectral Theory’: EPSRC workshop (1993).