RESEARCH PUBLICATIONS
1. K.
Ifantis, Uber das Eigenwertproblem der Funktional Gleichung f(x+a)+f(x-a)=2(E-b\x)f(x),
Zeits. Angew. Math. Mech. 48, (1968),66-68 (German)
- E. K.
Ifantis and P. C. Deliyiannis, Spectral Theory of the Difference
Equation f(n+1)+f(n-1)=(E-ö(n))f(n), J. Math. Phys. 10, (1969),
421-425
- E. K.
Ifantis, Spectral Theory of Tridiagonal operators, Bull. Greek
Math. Soc. 10, (1969),89-125. (In Greeks)
- E. K.
Ifantis, Structure of the Point spectrum of Schrodinger- Type
Tridiagonal Operators, J. Math. Phys. 11, (1970), 3138-3144
- E. K.
Ifantis, Abstract Formulation of the Quantum Mechanical oscillator
Phase Problem. J. Math. Phys. 12, (1971), 1021-1026
- E. K.
Ifantis, Solution of the Schrodinger Equation in the Hardy-Lebesgue
Space, J. Math. Phys. 12, (1971), 1961-1965
- E. K.
Ifantis, Minimal Uncertainty States for bounded Observables, J.
Math. Phys. 12, (1971), 2512-2516
- E. K.
Ifantis, On the Nature of the Spectrum of generalized oscillator Phase
Operators, Letters all Nouvo Cimento, 2, (1971), 1096-1100
- E. K.
Ifantis, States, minimizing the Uncertainty Product of the oscillator
Phase Operators, J. Math. Phys. 13, (1972), 568-575
- E. K.
Ifantis and C. B. Kouris, Study of Differential Equations of Mathematical
Physics in the Hardy-Lebesgue Space, J. Math. Phys. 13, (1972),
1193-1195.
- E. K.
Ifantis, Perturbation of Isometries, Duke Mathematical Journal,
39, (1972), 735-736.
- E. K.
Ifantis and C. B. Kouris, A Hilbert Space approach to the Localization
problem of the roots of Analytic Functions, Indiana University
Mathematics Journal, 23, (1973), 11-22.
- E. K.
Ifantis and C. B. Kouris, Lower Bounds for the Zeros of Analytic
Functions, Numer. Math. 27, (1976), 239-247.
- E. K.
Ifantis, An Existence Theory for Functional-Differential Equations and
Functional-Differential Systems, Jour. Diff. Equations, 29, (1978),
86-104.
- E. K.
Ifantis, and P. D. Siafarikas, and C. B. Kouris,
Conditions for Solutions of a linear First-Order Differential Equation
in the Hardy- Lebesgue Space and Applications, Jour. Math. Anal.
Appl. 104 (1984), 454-466.
- E. K.
Ifantis and P. D. Siafarikas, An Inequality relating the zeros of two
Ordinary Bessel Functions, Applicable Analysis, 19, (1985), 251-263.
- E. K.
Ifantis and P. D. Siafarikas, A Differential Equation for the Zeros of
Bessel Functions, Applicable Analysis, 20, (1985), 269-281.
- E. K.
Ifantis and P. D. Siafarikas, Ordering Relations Between the Zeros of
Miscellaneous Bessel Functions, Applicable Analysis, 23, (1986),
85-110.
- E. K.
Ifantis and P. D. Siafarikas, A Functional Analytic Approach for the
study of the zeros of Bessel Functions, Linear Algebra Appl. 84,
(1986),391-397.
- E. K.
Ifantis and P. D. Siafarikas, Upper Bounds for the Zeros of Bessel
Functions, Journal of Computational and Applied Mathematics, 17,
(1987), 355-358.
- E. K.
Ifantis, Analytic Solutions for Nonlinear Differential Equations, Journal
of Mathematical Analysis and Applications, 124 (2), (1987),
339-380.
- E. K.
Ifantis, Global Analytic Solutions of the Radial Nonlinear Wave
Equation, Journal of Mathematical Analysis and Applications, 124 (2),
(1987), 381-3-410.
- E. K.
Ifantis, On the Convergence of Power series Whose Coefficients Satisfy
a Poincare-type linear and non linear Difference Equation, Complex
Variables, 9, (1987), 63-80.
- E. K.
Ifantis and P. D. Siafarikas, A Differential Equation for the Positive
Zeros of the Function $\alpha J\sb v(z)+\gamma zJ'\sb v(z)$, Zeitschrist
fur Analysis and Ihre Anwendungen, 7 (2), (1988), 185-192.
- E. K.
Ifantis, P. D. Siafarikas and C. B. Kouris, The Imaginary zeros of a
mixed Bessel Function, Journal of Applied Mathematics and
Physics, 39, (1988), 157-165.
26. E. K. Ifantis,
A Theorem Concerning Differentiability of Eigenvectors and Eigenvalues with
some Applications, Applicable Analysis, 28 (1988), 257-283.
- E. K.
Ifantis and P. D. Siafarikas, Bounds for the first positive Zero of a
mixed Bessel Function, Journal of Computational and Applied Mathematics,
21, (1988), 245-249.
- E. K.
Ifantis and P. D. Siafarikas, Differential Inequalities on the
greatest Zeros of Laguerre and Ultraspherical Polynomials, Actas del VI
Simposium on Polinomios Orthogonales Y aplicationes, Gilon, Spain, (1989),
187-197.
- E. K.
Ifantis and P. D. Siafarikas, A result on the Imaginary Zeros of
$J"\sb \nu(z)$, Journal of Approximation Theory,
62 (2), (1990), 192-196.
- E. K.
Ifantis and P. D. Siafarikas, Inequalities involving Bessel and
Modified Bessel Functions, Journal Math. Anal. Appl. 147, (1990),
214-227.
- E. K.
Ifantis and P. D. Siafarikas, Differential Inequalities for the
positive zeros of Bessel Functions, Journal of Computational and
Applied Mathematics, 30, (1990),139-143.
- E. K.
Ifantis and P. N. Panagopoulos, Applications of the
differentiability of eigenvectors and eigenvalues to a perturbed harmonic
oscillator, Jour. Math. Physics, 31, (1990), 2410-2413.
- E. K.
Ifantis and P. D. Siafarikas, Bounds of Modified Bessel Functions, Rendiconti
del Circolo Matematico Di Palermo, Serie II, Tomo XL, (1991),
347-356.
- E. K.
Ifantis, Concavity and Convexity of Eigenvalues, Applicable
Analysis, 41, (1991), 209-220.
- E. K.
Ifantis and C. G. Kokologiannaki and C. B. Kouris, On the Positive zeros
of the second derivative of Bessel functions, Journal of Computational
and Applied Math. 34, (1991), 21-31.
- E. K.
Ifantis, Perron-Frobenious-Type Theorems for Tridiagonal Operators, Applicable
Analysis, 44, (1992), 159-169.
- E. K.
Ifantis and P. D. Siafarikas, A Differential Inequality for the
positive zeros of Bessel Functions, Journal of Computational and
Applied Math., 44, (1992), 115-120.
- E. K.
Ifantis and P. D. Siafarikas, and A. P. Jannusis, Entire Solution of a
Second Order Linear Differential Equation, Complex Variables, 22,
(1993), 23-26,.
- E. K.
Ifantis and P. D. Siafarikas, On the Zeros of a Class of Polynomials
including the generalized Bessel Polynomials, Proceedings of the Seventh Spanish
Symposium on Orthogonal Polynomials and Applications (VII SPOA) (Granada,
1991), Jour. Comp. Appl. Math. 49. (1993), 103-109.
- E. K.
Ifantis and C. G. Kokologiannaki, Location of the complex zeros of
Bessel functions, Zeits. fur Analysis und Ihre Andwendungen,
12 (4), (1993), 605-612.
- E. K.
Ifantis and P. N. Panagopoulos, On the Zeros of a Class of
Polynomials, J. Math. Anal. Appl. 182 (2), (1994), 361-370.
- E. K.
Ifantis and P. D. Siafarikas, Perturbation of the Coefficients in the
recurrence relation of a Class of Polynomials, J. Comp. Appl. Math.
57, (1995), 163-170.
- E. K.
Ifantis and P. D. Siafarikas, Differential Inequalities and
Monotonicity Properties of the Zeros of Associated Laquerre and Hermite
Polynomials, Annals Numer. Math. 2, (1995), 79-91.
- E. K.
Ifantis and P. D. Siafarikas, An Alternative proof of a theorem of
Stieltjes and related results, J. Comp. Appl. Math. 65, (1995),
165-172.
- E. K.
Ifantis and P. D. Siafarikas and C. G. Kokologiannaki, Newton sum
rules and monotonicity properties of zeros of scaled co-recursive
associated polynomials, Methods and Applications of Analysis, 3
(4), (1996), 486-497.
- E. K.
Ifantis, A criterion for the non-uniqueness of the measure of
orthogonality, Jour. Appr. Theory, 89, (1997), 207-218.
- E. K
Ifantis and K. N. Vlachou, Some results, concerning the variation of
eigenvalues, when these depend on a real parameter. Appl. Anal. 74 (2000),
no. 1-2, 113-125.
- E. K.
Ifantis and P. N. Panagopoulos, Convergence of associated continued
fractions revised. Acta Appl. Math. 66 (2001), no. 1, 1-24.
- E. K.
Ifantis and P. N. Panagopoulos, Limit points of eigenvalues of
truncated tridiagonal operators, J. Comp. Appl. Math. 133 (1-2) (2001),
413-422 (Special Issue: Orthogonal Polynomials, Special Functions and
their Applications)
- E. K.
Ifantis, On the spectral measure of a class of orthogonal polynomials,
Open Problem, J. Comp. Appl. Math. 133 (1-2) (2001), 688-689 (Special
Issue: Orthogonal Polynomials, Special Functions and their Applications)
- E. K. Ifantis, P. D. Siafarikas, A counterexample to
an assertion due to Blumenthal. Univ. Iagel. Acta Math. Vol.. 39 (2001),
249-254.
- E. K.
Ifantis, C. G. Kokologiannaki and P. D. Siafarikas, On the support of the measure of
orthogonality of a class of orthogonal polynomials, Applied
Mathematics and Computation Vol. 128 (2-3) (2002), 275-288.
- E. K. Ifantis and K. N. Vlachou, Solution of
the semi-infinite Toda lattice for unbounded sequences, Lett. Math. Phys. Vol. 59 (2002), 1-17
- E. K.
Ifantis and C. G. Kokologiannaki, Stieltjes transforms of a class of
probability measure, J. Comput. Appl. Math.
Vol.153 (2003), no. 1-2, 249–258
- E. K. Ifantis and K. N. Vlachou, Exact
solutions of the semi-infinite Toda lattice with applications to the
inverse spectral problem, Absr. Appl. Anal. 2004, no. 5,
435-451.
- E. K. Ifantis, C. G. Kokologiannaki
and E. Petropoulou, Limit points of eigenvalues of
truncated unbounded tridiagonal operators, Cent. Eur. J. Math. Vol. 5
(2007), no. 2, 335–344.