Curiculum vitae:
Dragoljub J. Kečkić was born on March 20th, 1972 in Belgrade. He graduated on 26 June 1995. at the Faculty of Mathematics, University of Belgrade, Department for theoretical mathematics and applications. Master's thesis titled "Elementary mappings on the ideals of compact operators in Hilbert space", defended on December 8th 1998. PhD thesis, "The structure of tha range and the kernel of elementary operators" defended on June 12th 2003. Since 1995. to 1999. employed at the Faculty of Mathematics in Belgrade, as a teaching assistant. Since 1999. to 2003. worked as an assistant, since October 2003. as assistant professor, since May 2013. as associated professor and since 2019 as full profdessor. Area of interest: Theory of operators on Hilbert spaces, C*- algebras and other operator algebras.
Teaching (in serbian language):
Written texts
- Lebesgue points - measure theory;
- Real numbers;
- Exponential and logarithmic function;
- Trigonometric functions;
- Uniform convergence;
- Integrals depending on a parameter;
- Fourier series;
- Functional analysis - selected topics (beta version);
- Analysis 3B;
Exam questions (in serbian language)
Video clips (also in serbian langauage)
Papers:
- Elementary mappings on the ideals of compact operators on a Hilbert space - M.A. thesis (in Serbian);
- Orthogonality of the range and the kernel of some elementary operators, Proc. Amer. Math. Soc.128-11(2000), pp.3369-3377;
- On the operator equation AX-XB=Y, Proceedings of the 10th CONGRESS OF YUGOSLAV MATHEMATICIANS, pp.247-250
- Bergman spaces on the complement of a lattice (with M. Arsenović), Arkhiv der Mathematik, 81-5(2003), pp.575-584;
- Orthogonality in S1 and S∞ spaces and normal derivations, J Oper. Theory, 51-1(2004), pp.89-104;
- The structure of the range and the kernel of elementary operators - PhD thesis (in Serbian);
- Gateaux derivative of B(H) norm, Proc. Amer. Math. Soc., 133-7(2005), pp.2061-2067;
- Elementary operators on Banach algebras and Fourier transform (with M. Arsenović), Studia Math, 173(2006), pp.149-166;
- A Counterexample on a Theorem by Khojasteh, Goodarzi, and Razani (with I. Aranđelović), Fixed point theory and applications, Article ID 470141, 6 pages, doi:10.1155/2010/470141
- A functional calculus for unbounded generalized scalar operators on Banach spaces (with Đ. Krtinić), Pacific J Math, 249-1(2011), pp.135-156
- On nonlinear quasi-contractions on TVS-cone metric spaces (with I. Aranđelović), Appl. Math. Lett, 24-7(2011), pp.1209-1213
- Symmetric spaces approach to some fixed point results (with I. Aranđelović), Nonlinear Analysis, 75(2012), pp. 5157-5168
- Cyclic kernels of elementary operators on Banach spaces, Linear Algebra Appl., 438-5(2013), pp. 2628-2633
- Orthogonality and smooth points in C(K) and Cb(Ω), Eurasian Math. J.,3-4(2012), pp. 44-52
- On the index of product systems of Hilbert modules (with B. Vujošević), Filomat,29-5(2015), pp. 1093-1111
- Compact and "compact" operators on standard Hilbert modules over W*-algebras (with Z. Lazović), Ann. Funct. Anal.,9-2(2018), pp. 258-270
- Fredholm operators on C*-algebras (with Z. Lazović), Acta Sci. Math. (Szeged),83, 3-4(2017), pp. 629-655
- Measures of noncompactness on the standard Hilbert C*-module (with Z. Lazović), Filomat, 33-12(2019)
- Continuous generalization of Clarkson-McCarthy inequalities, Banach J Math. Anal.,13, 1(2019), pp. 26-46
- The applications of Cauchy-Schwartz inequality for Hilbert modules to elementary operators and i.p.t.i. transformers, Appl. Anal. Discrete Math. 14(2020), pp. 169--182
- Isolated vertices and diameter of the BJ-orthograph in C*-algebras (with S. Stefanović), J Math. Anal. App., 528-1(2023), 127476