Derkach, Volodymyr; Hassi, Seppo; Malamud, Mark Generalized boundary triples. II: Some applications of generalized boundary triples and form domain invariant Nevanlinna functions. (English) Zbl 07747288 Math. Nachr. 295, No. 6, 1113-1162 (2022). MSC: 47A10 47A20 47B25 34B08 35J25 34B40 34L40 35J05 47B36 47E05 47F05 PDFBibTeX XMLCite \textit{V. Derkach} et al., Math. Nachr. 295, No. 6, 1113--1162 (2022; Zbl 07747288) Full Text: DOI OA License
Behrndt, Jussi; Hassi, Seppo; de Snoo, Henk Boundary value problems, Weyl functions, and differential operators. (English) Zbl 1457.47001 Monographs in Mathematics 108. Cham: Birkhäuser (ISBN 978-3-030-36713-8/hbk; 978-3-030-36716-9/pbk; 978-3-030-36714-5/ebook). vii, 772 p., open access (2020). Reviewer: Andreas Fleige (Dortmund) MSC: 47-02 47Axx 47Bxx 47E05 47Fxx 34Bxx 34Lxx 35Pxx 93Bxx PDFBibTeX XMLCite \textit{J. Behrndt} et al., Boundary value problems, Weyl functions, and differential operators. Cham: Birkhäuser (2020; Zbl 1457.47001) Full Text: DOI Link
Hassi, Seppo; Malamud, Mark; Mogilevskii, Vadim Unitary equivalence of proper extensions of a symmetric operator and the Weyl function. (English) Zbl 1285.47018 Integral Equations Oper. Theory 77, No. 4, 449-487 (2013). MSC: 47A56 47B25 47A48 47E05 PDFBibTeX XMLCite \textit{S. Hassi} et al., Integral Equations Oper. Theory 77, No. 4, 449--487 (2013; Zbl 1285.47018) Full Text: DOI arXiv
Malamud, M. M.; Mogilevskii, V. I.; Hassi, S. On the unitary equivalence of the proper extensions of a Hermitian operator and the Weyl function. (English. Russian original) Zbl 1285.47019 Math. Notes 91, No. 2, 302-307 (2012); translation from Mat. Zametki 91, No. 2, 316-320 (2012). MSC: 47A56 47B25 47A48 47E05 PDFBibTeX XMLCite \textit{M. M. Malamud} et al., Math. Notes 91, No. 2, 302--307 (2012; Zbl 1285.47019); translation from Mat. Zametki 91, No. 2, 316--320 (2012) Full Text: DOI
Hassi, Seppo (ed.); de Snoo, Hendrik S. V. (ed.); Szafraniec, Franciszek Hugon (ed.) Operator methods for boundary value problems. (English) Zbl 1269.47001 London Mathematical Society Lecture Note Series 404. Cambridge: Cambridge University Press (ISBN 978-1-107-60611-1/pbk; 978-1-139-13506-1/ebook). xii, 298 p. (2012). MSC: 47-06 47E05 47B25 35J25 35S05 00B15 PDFBibTeX XMLCite \textit{S. Hassi} (ed.) et al., Operator methods for boundary value problems. Cambridge: Cambridge University Press (2012; Zbl 1269.47001) Full Text: DOI
Behrndt, Jussi; Hassi, Seppo; De Snoo, Henk; Wietsma, Rudi Square-integrable solutions and Weyl functions for singular canonical systems. (English) Zbl 1232.34037 Math. Nachr. 284, No. 11-12, 1334-1384 (2011). Reviewer: Petr Zemanek (Brno) MSC: 34B20 34B05 34A30 47E05 PDFBibTeX XMLCite \textit{J. Behrndt} et al., Math. Nachr. 284, No. 11--12, 1334--1384 (2011; Zbl 1232.34037) Full Text: DOI
Fleige, Andreas; Hassi, Seppo; de Snoo, Henk; Winkler, Henrik Sesquilinear forms corresponding to a non-semibounded Sturm-Liouville operator. (English) Zbl 1187.47006 Proc. R. Soc. Edinb., Sect. A, Math. 140, No. 2, 291-318 (2010). MSC: 47A07 47B25 34B24 47E05 47A70 PDFBibTeX XMLCite \textit{A. Fleige} et al., Proc. R. Soc. Edinb., Sect. A, Math. 140, No. 2, 291--318 (2010; Zbl 1187.47006) Full Text: DOI
Hassi, S.; De Snoo, H. S. V.; Sterk, A. E.; Winkler, H. Finite-dimensional graph perturbations of selfadjoint Sturm-Liouville operators. (English) Zbl 1199.34132 Bakonyi, Mihály (ed.) et al., Operator theory, structured matrices, and dilations. Tiberiu Constantinescu memorial volume. Bucharest: Theta (ISBN 978-973-87899-0-6). Theta Series in Advanced Mathematics 7, 205-228 (2007). MSC: 34B20 34L10 47E05 47B25 PDFBibTeX XMLCite \textit{S. Hassi} et al., Theta Ser. Adv. Math. 7, 205--228 (2007; Zbl 1199.34132)
Hassi, Seppo; De Snoo, Henk; Sterk, Alef; Winkler, Henrik Nonstandard boundary conditions for a class of Sturm-Liouville problems. (English) Zbl 1120.34015 Rev. Roum. Math. Pures Appl. 51, No. 5-6, 641-653 (2006). MSC: 34B20 34L10 47E05 34B10 47A57 PDFBibTeX XMLCite \textit{S. Hassi} et al., Rev. Roum. Math. Pures Appl. 51, No. 5--6, 641--653 (2006; Zbl 1120.34015)
Fleige, Andreas; Hassi, Seppo; de Snoo, Henk; Winkler, Henrik Generalized Friedrichs extensions associated with interface conditions for Sturm–Liouville operators. (English) Zbl 1111.47037 Langer, Matthias (ed.) et al., Operator theory and indefinite inner product spaces. Presented on the occasion of the retirement of Heinz Langer in the colloquium on operator theory, Vienna, March 2004. Basel: Birkhäuser (ISBN 3-7643-7515-9/hbk). Operator Theory: Advances and Applications 163, 135-145 (2006). Reviewer: Petru A. Cojuhari (Kraków) MSC: 47E05 47B25 47A10 34B05 34B24 PDFBibTeX XMLCite \textit{A. Fleige} et al., Oper. Theory: Adv. Appl. 163, 135--145 (2006; Zbl 1111.47037)
Karabash, I. M.; Hassi, S. Similarity between \(J\)-self-adjoint Sturm–Liouville operators with operator potential and self-adjoint operators. (English. Russian original) Zbl 1116.47039 Math. Notes 78, No. 4, 581-585 (2005); translation from Mat. Zametki 78, No. 4, 625-628 (2005). Reviewer: Rudolf Kodnár (Bratislava) MSC: 47E05 34L40 47A10 47B50 47F05 35J10 PDFBibTeX XMLCite \textit{I. M. Karabash} and \textit{S. Hassi}, Math. Notes 78, No. 4, 581--585 (2005; Zbl 1116.47039); translation from Mat. Zametki 78, No. 4, 625--628 (2005) Full Text: DOI
Hassi, Seppo; Möller, Manfred; de Snoo, Henk Singular Sturm-Liouville problems whose coefficients depend rationally on the eigenvalue parameter. (English) Zbl 1058.34028 J. Math. Anal. Appl. 295, No. 1, 258-275 (2004). Reviewer: Victor S. Rykhlov (Saratov) MSC: 34B24 34B20 47E05 PDFBibTeX XMLCite \textit{S. Hassi} et al., J. Math. Anal. Appl. 295, No. 1, 258--275 (2004; Zbl 1058.34028) Full Text: DOI
Oridoroga, L. L.; Khassi, S. Completeness theorems for Dirac-type operators with boundary conditions of general form that depend on the spectral parameter. (English. Russian original) Zbl 1064.34075 Math. Notes 74, No. 2, 302-307 (2003); translation from Mat. Zametki 74, No. 2, 316-320 (2003). Reviewer: Victor S. Rykhlov (Saratov) MSC: 34L40 34B05 34L10 47E05 PDFBibTeX XMLCite \textit{L. L. Oridoroga} and \textit{S. Khassi}, Math. Notes 74, No. 2, 302--307 (2003; Zbl 1064.34075); translation from Mat. Zametki 74, No. 2, 316--320 (2003) Full Text: DOI
Hassi, Seppo; Moiled, Manfred; de Snoo, Henk Differential operators and spectral functions. (English) Zbl 1104.34314 Ukrainian mathematical congress – 2001, Kiev, Ukraine, August 21–23, 2001. Proceedings. Section 11. Functional analysis. Kyïv: Instytut Matematyky NAN Ukraïny (ISBN 966-02-2779-5). 313-322 (2002). MSC: 34B24 47E05 34L40 34L05 PDFBibTeX XMLCite \textit{S. Hassi} et al., in: Ukraïns'kyj matematychnyj kongres -- 2001. Pratsi. Sektsiya 11. Funktsional'nyj analiz. Kyïv: Instytut Matematyky NAN Ukraïny. 313--322 (2002; Zbl 1104.34314)
Hassi, Seppo; Remling, Christian; de Snoo, Henk Subordinate solutions and spectral measures of canonical systems. (English) Zbl 0967.34073 Integral Equations Oper. Theory 37, No. 1, 48-63 (2000). MSC: 34L05 34B20 47B25 47E05 PDFBibTeX XMLCite \textit{S. Hassi} et al., Integral Equations Oper. Theory 37, No. 1, 48--63 (2000; Zbl 0967.34073) Full Text: DOI
Hassi, Seppo; de Snoo, Henk; Winkler, Henrik Boundary-value problems for two-dimensional canonical systems. (English) Zbl 0966.47012 Integral Equations Oper. Theory 36, No. 4, 445-479 (2000). Reviewer: André Noll (Darmstadt) MSC: 47B25 47A20 47E05 34B20 34A55 34L05 PDFBibTeX XMLCite \textit{S. Hassi} et al., Integral Equations Oper. Theory 36, No. 4, 445--479 (2000; Zbl 0966.47012) Full Text: DOI