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Homepage of Bozhidar Velichkov

Professore Ordinario (Full Professor) at
Dipartimento di Matematica
Università di Pisa

I am working in the fields of
Calculus of Variations and Partial Differental Equations,
in particular on the Regularity Theory, which is the study of the
fine structure of the solutions to variational and PDE problems.
Most of my current research is dedicated to Free Boundary Problems.

Selected
results

Free boundary minimal surfaces


Some remarks on singular capillary cones with free boundary
(preprint 02/2025; with Alberto Pacati and Giorgio Tortone)

Optimal partition problems and harmonic maps

Evolution free boundary problems


An elliptic regularization approach to the Stefan problem
(preprint 6/2026; with Filippo Paiano)

One-phase Bernoulli free boundaries

Uniqueness of the blow-up at isolated singularities for the Alt-Caffarelli functional
(Duke Math. J. 2020; with Max Engelstein and Luca Spolaor)

The two-phase Bernoulli problem


Fine structure of the two-phase Bernoulli free boundaries in 2D
(preprint 7/2024; with Lorenzo Ferreri and Luca Spolaor)


(Quasi-)conformal methods in two-dimensional free boundary problems
(J. Eur. Math. Soc. 2024; with Guido De Philippis and Luca Spolaor)


Regularity of the optimal sets for the second Dirichlet eigenvalue
(Ann. Inst. H. Poincaré Anal. Non Linéaire 2022; with Dario Mazzoleni, Baptiste Trey)

       - Summary/Cover letter

Vectorial problems and free boundary systems


On a multiphase vectorial Bernoulli free boundary problem
(preprint 5/2026; with Giovanni Siclari)


On the blow-up of the vectorial Bernoulli free boundary problem
(preprint 2/2026; with Giovanni Siclari)


Regularity of the optimal sets for a class of integral shape functionals
(Arch. Rat. Mech. Anal. 2024; with G. Buttazzo, F.P. Maiale, D. Mazzoleni, G. Tortone)


The boundary Harnack principle on optimal domains
(Ann. Sc. Norm. Super. Pisa Cl. Sci. 2024; with F. P. Maiale and Giorgio Tortone)

Regularity of the free boundary for the vectorial Bernoulli problem
(Anal. PDE 2020; with Dario Mazzoleni and Susanna Terracini)


Regularity of the optimal sets for some spectral functionals

(Geom. Funct. Anal. 2017; with Dario Mazzoleni and Susanna Terracini)

Obstacle problems


Books


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