Tudor Zamfirescu

Prof. Dr. Tudor Zamfirescu

Department of Mathematics, Dortmund University of Technology, 44227 Dortmund, Germany

Research Focus & Metrics

Academic Career Length

29Years (1998-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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1 April 1998 in Transactions of the American Mathematical Society
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TZTudor Zamfirescu
Tudor Zamfirescu
We first see that, in the sense of Baire categories, many convex surfaces have quite large cut loci and infinitely many relative maxima of the distance function from a point. Then we find that, on any convex surface, all these extreme points lie on a single subtree of the cut locus, with at most three endpoints. Finally, we confirm (both in the sense of measure and in the sense of Baire categories) Steinhaus’ conjecture that “almost all" points admit a single farthest point on the surface.

26 January 2007 in Advances in Geometry
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CVCostin Vîlcu
Costin Vîlcu
TZTudor Zamfirescu
Tudor Zamfirescu
The farthest point mapping on compact surfaces, associating to each point x of the surface the set of absolute maxima of the intrinsic distance from x, is for some surfaces single-valued and a homeomorphism, while for other surfaces it is not single-valued, and not surjective. These two big classes are not very well understood. For instance it is still unknown whether, say in the convex case, the second class is dense. For a C2 metric on both surfaces and the space of surfaces, the first class has, however, nonempty interior. We describe various properties of the sets of critical points, and of relative and absolute maxima of distance functions, and find several connections between them. We see for example that, on smooth surfaces homeomorphic to S2, a point cannot be critical with respect to more than one other point. Sufficient conditions for a surface to belong to the second class will be formulated and a particular Tannery surface belonging to the boundary of both classes will be presented.

1 July 2006 in Advances in Geometry
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CVCostin Vîlcu
Costin Vîlcu
TZTudor Zamfirescu
Tudor Zamfirescu
Consider the mapping F associating to each point x of a convex surface the set of all points at maximal intrinsic distance from x. We provide a large class of surfaces on which F is single-valued and involutive. Moreover, we show that there are point-symmetric surfaces of revolution with F single-valued but not involutive.

1 September 2000 in Discrete & Computational Geometry
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JRJ. R. Reay
J. R. Reay
TZTudor Zamfirescu
Tudor Zamfirescu

1 February 2004 in Discrete & Computational Geometry
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JIJin-Ichi Itoh
Jin-Ichi Itoh
TZTudor Zamfirescu
Tudor Zamfirescu

24 May 2018 in The American Mathematical Monthly
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YCYing Chai
Ying Chai
LYLiping Yuan
Liping Yuan
TZTudor Zamfirescu
Tudor Zamfirescu
We say that a polytope has the Rupert property if we can make a hole large enough in to permit another copy of to pass through. In this article, we show that among the 13 Archimedean solids, 8 have this property, namely, the cuboctahedron, the truncated octahedron, the truncated cube, the rhombicuboctahedron, the icosidodecahedron, the truncated cuboctahedron, the truncated icosahedron, and the truncated dodecahedron.