Physical Sciences and Mathematics Commons^™

Automorphisms Of Free Groups With Boundaries, Craig A. Jensen, Nathalie Wahl

Mathematics Faculty Publications

The automorphisms of free groups with boundaries form a family of groups An,k closely related to mapping class groups, with the standard automorphisms of free groups as An,0 and (essentially) the symmetric automorphisms of free groups as A0,k. We construct a contractible space Ln,k on which An,k acts with finite stabilizers and finite quotient space and deduce a range for the virtual cohomological dimension of An,k. We also give a presentation of the groups and calculate their first homology group.

Homology Of Holomorphs Of Free Groups, Craig A. Jensen

Mathematics Faculty Publications

Let Fn be the free group on n letters and let Aut(Fn), Out(Fn) denote the automorphism group and the outer automorphism group of Fn. In this paper the purpose is to obtain some new results on stability and to calculate the mod-p homology of the holomorph of Fn for odd primes in dimensions 1 and 2, and the rational homology in dimensions from 1 through 5.

On Classifying Finite Edge Colored Graphs With Two Transitive Automorphism Groups, Thomas Q. Sibley

Mathematics Faculty Publications

This paper classifies all finite edge colored graphs with doubly transitive automorphism groups. This result generalizes the classification of doubly transitive balanced incomplete block designs with λ=1 and doubly transitive one-factorizations of complete graphs. It also provides a classification of all doubly transitive symmetric association schemes.

Multiple Solutions For Quasilinear Elliptic Neumann Problems In Orlicz-Sobolev Spaces, Nikolaos Halidias, Vy Khoi Le

Mathematics and Statistics Faculty Research & Creative Works

We investigate the existence of multiple solutions to quasilinear elliptic problems containing Laplace like operators (ϕ-Laplacians). We are interested in Neumann boundary value problems and our main tool is Brézis-Nirenberg's local linking theorem.

Tid And See Testing Results Of Altera Cyclone Field Programmable Gate Array, Stephen L. Clark, K. Avery, R. Parker

Mathematics and Statistics Faculty Research & Creative Works

Total ionizing dose (TID) and single event effects testing was performed on Altera Cyclone FPGAs. The devices exhibit slight performance degradation to a TID of 1 Mrad (Si), but also exhibited single event latchup at a low LET.

The Independence Of Characters On Nonabelian Groups, David E. Grow, Kathryn E. Hare

Mathematics and Statistics Faculty Research & Creative Works

We show that there are characters of compact, connected, nonabelian groups that approximate random choices of signs. The work was motivated by Kronecker's theorem on the independence of exponential functions and has applications to thin sets.

Hereditarily Unicoherent Continua And Their Absolute Retracts, J. J. Charatonik, W. J. Charatonik, Janusz R. Prajs

Mathematics and Statistics Faculty Research & Creative Works

We investigate absolute retracts for classes of hereditarily unicoherent continua, tree-like continua, λ- dendroids, dendroids and some other related ones. The main results are: (1) the inverse limits of trees with confluent bonding mappings are absolute retracts of hereditarily unicoherent continua; (2) each tree-like continuum is embeddable in a special way in a tree-like absolute retract for the class of hereditarily unicoherent continua; (3) a dendroid is an absolute retract for hereditarily unicoherent continua if and only if it can be embedded as a retract into the Mohler-Nikiel universal smooth dendroid.

Existence And Comparison Results For Quasilinear Evolution Hemivariational Inequalities, Siegfried Carl, Vy Khoi Le, Dumitru Motreanu

Mathematics and Statistics Faculty Research & Creative Works

We generalize the sub-supersolution method known for weak solutions of single and multivalued nonlinear parabolic problems to quasilinear evolution hemivariational inequalities. To this end we first introduce our basic notion of sub- and supersolutions on the basis of which we then prove existence, comparison, compactness and extremality results for the hemivariational inequalities under considerations.

Oscillation Of Second Order Nonlinear Dynamic Equations On Time Scales, S. H. Saker, Martin Bohner

Mathematics and Statistics Faculty Research & Creative Works

By means of Riccati transformation techniques, we establish some oscillation criteria for a second order nonlinear dynamic equation on time scales in terms of the coefficients. We give examples of dynamic equations to which previously known oscillation criteria are not applicable.

Oscillation Theory For Second Order Dynamic Equations [Book Review], Martin Bohner

Mathematics and Statistics Faculty Research & Creative Works

No abstract provided.

Quantum Deformations Of Fundamental Groups Of Oriented 3-Manifolds, Uwe Kaiser

Mathematics Faculty Publications and Presentations

We compute two-term skein modules of framed oriented links in oriented 3-manifolds. They contain the self-writhe and total linking number invariants of framed oriented links in a universal way. The relations in a natural presentation of the skein module are interpreted as monodromies in the space of immersions of circles into the 3-manifold.

An Informal Introduction To Computing With Chern Classes, Zach Teitler

Zach Teitler

Some time ago, Dr. Teitler began work on a short expository set of notes on Chern classes in algebraic geometry, particularly in the context of enumerative problems. The notes are not polished. Some day he hopes to finish them; in the meantime, here is a draft, in PDF format (21 pages).

Miniaturen. Studien Zu Kalkül Und Kreativität 1998-2002, Rudolf Kaehr

Rudolf Kaehr

Informatik, künstlerische Praktik und Kunsttheorie der digitalen Bildtechnologien NULL&NICHTS; weder leer, noch nicht – oder Kraut und Rüben Gedanken zu einer autonomen Medienwissenschaft Das Menschenbild aus der Sicht einer polykontexturalen Systemtheorie Thesen zum trans-klassischen Menschenbild Gebaute Phantasien, unkontrollierbare Schwankungen Kreativität und Kalkül Ver_Endungen in/der Programmierbarkeit Diagrammatik: Denken a la Carte Zur Verstörung des (H)ortes der Zerstörung Zur Kenogrammatik der Medientheorie

Dynamic Semantic Web, Rudolf Kaehr

Rudolf Kaehr

Dynamic Semantic Web (DSW) is based at first on the techniques, methods and paradigms of the emerging Semantic Web movement and its applications. DSW is advancing one fundamental step further from a static to a dynamic concept of the Semantic Web with extended flexibility in the navigation between ontologies and more profound transparency of the informational system. Web Services are now redefinded by Semantic Web. To proof the advantages of DSW, it is the main aim of this project to develop the tools and methods necessary to develop a DSW based Web Service (DSW business application). The existing framework of …

Uniqueness Theorems In Bioluminescence Tomography, Ge Wang, Yi Li, Ming Jiang

Yi Li

Motivated by bioluminescent imaging needs for studies on gene therapy and other applications in the mouse models, a bioluminescence tomography (BLT) system is being developed in the University of Iowa. While the forward imaging model is described by the well-known diffusion equation, the inverse problem is to recover an internal bioluminescent source distribution subject to Cauchy data. Our primary goal in this paper is to establish the solution uniqueness for BLT under practical constraints despite the ill-posedness of the inverse problem in the general case. After a review on the inverse source literature, we demonstrate that in the general case …

A Counterexample In Sturm-Liouville Completeness Theory, Paul Binding, Branko Ćurgus

Mathematics Faculty Publications

We give an example of an indefinite weight Sturm-Lionville problem whose eigenfunctions form a Riesz basis under Dirichlet boundary conditions but not under anti-periodic boundary conditions.

A Contraction Of The Lucas Polygon, Branko Ćurgus

Mathematics Faculty Publications

The celebrated Gauss-Lucas theorem states that all the roots of the derivative of a complex non-constant polynomial p lie in the convex hull of the roots of p, called the Lucas polygon of p. We improve the Gauss-Lucas theorem by proving that all the nontrivial roots of p^' lie in a smaller convex polygon which is obtained by a strict contraction of the Lucas polygon of p.

An Inverse Problem For The Transport Equation In The Presence Of A Riemannian Metric, Stephen R. Mcdowall

Mathematics Faculty Publications

The stationary linear transport equation models the scattering and absorption of a low-density beam of neutrons as it passes through a body. In Euclidean space, to a first approximation, particles travel in straight lines. Here we study the analogous transport equation for particles in an ambient field described by a Riemannian metric where, again to first approximation, particles follow geodesics of the metric. We consider the problem of determining the scattering and absorption coefficients from knowledge of the albedo operator on the boundary of the domain. Under certain restrictions, the albedo operator is shown to determine the geodesic ray transform …

Optical Design Of Two-Reflector Systems, The Monge-Kantorovich Mass Transfer Problem And Fermat’S Principle, Tilmann Glimm, Vladimir Oliker

Mathematics Faculty Publications

It is shown that the problem of designing a two-reflector system transforming a plane wave front with given intensity into an output plane front with prescribed output intensity can be formulated and solved as the Monge-Kantorovich mass transfer problem.

Numbers In The Sky(Viewing Sculpture), Branko Ćurgus

Mathematics Faculty Publications

The following is my personal exploration of Noguchi’s sculpture inspired by what I do most of the time: math, or playing with numbers. His sculpture is very geometric; it lends itself to mathematical explorations, and I decided to look for a mathematical message in it.

I think Skyviewing Sculpture is really beautiful, and I have also encountered a lot of beautiful things in math, so the natural thing was to look for a connection: the beautiful sculpture giving rise to beautiful math. This is a short report of what I found. There is much more to be discovered, and these …

A Quasi-Linear Manifolds And Quasi-Linear Mapping Between Them, Aki̇f Abbasov

Turkish Journal of Mathematics

In this article a special class of Banach manifolds (called QL-manifolds) and mapping between them (QL-mappings) are introduced and some examples are given.

On Graded Primary Ideals, Mashhoor Refai, Khaldoun Al-Zoubi

Turkish Journal of Mathematics

Let G be a group and R be a G-graded commutative ring, i.e., R = \oplus_{g \in G} R_g and R_gR_h \subseteq R_{gh} for all g, h \in G. In this paper, we study the graded primary ideals and graded primary G-decomposition of a graded ideal.

Determination Of A Fractional-Linear Pencil Of Sturm-Liouville Operators By Two Of Its Spectra, R. T. Pashayev

Turkish Journal of Mathematics

In this paper we consider the Sturm-Liouville equations on a finite interval which is fractional-linear in the spectral parameter. The inverse spectral problem consisting of the recovering of the operator from the two spectra is investigated and a uniqueness theorem for solution of the inverse problem is proved.

Perelman's Monotonicity Formula And Applications, Natasa Sesum

Turkish Journal of Mathematics

This article relies on [15] that the author wrote with Gang Tian and Xiaodong Wang. In view of Hamilton's important work on the Ricci flow and Perelman's paper on the Ricci flow where he developes the techniques that he will later use in completing Hamilton's program for the geometrization conjecture, there may be more interest in the area. We will also discuss the author's theorem which says that the curvature tensor stays uniformly bounded under the unnormalized Ricci flow in a finite time, if the curvatures are uniformly bounded. We will prove that in the case of a Kähler-Ricci flow …

Flops Of Crepant Resolutions, Anda Degeratu

Turkish Journal of Mathematics

Let G be a finite subgroup of SL(3, \mathcal{C}) acting with an isolated singularity on \mathcal{C}^3. A crepant resolution of \mathcal{C}^3/G comes together with a set of tautological line bundles associated to each irreducible representation of G. In this note we give a formula for the triple product of the first Chern class of the tautological bundles in terms of both the geometry of the crepant resolution and the representation theory of G. From here we derive the way these triple products change when we perform a flop.

The Cross Curvature Flow Of 3-Manifolds With Negative Sectional Curvature, Bennett Chow, Richard S. Hamilton

Turkish Journal of Mathematics

We consider the cross curvature flow, an evolution equation of metrics on 3-manifolds. We establish short time existence when the sectional curvature has a sign. In the case of negative sectional curvature, we obtain some monotonicity formulas which support the conjecture that after normalization, for initial metrics on closed 3-manifolds with negative sectional curvature, the solution exists for all time and converges to a hyperbolic metric. This conjecture is still open at the present time.

Surgery Diagrams For Contact 3-Manifolds, Fan Ding, Hansjörg Geiges, Andras I. Stipsicz

Turkish Journal of Mathematics

In two previous papers, the two first-named authors introduced a notion of contact r-surgery along Legendrian knots in contact 3-manifolds. They also showed how (at least in principle) to convert any contact r-surgery into a sequence of contact (\pm 1)-surgeries, and used this to prove that any (closed) contact 3-manifold can be obtained from the standard contact structure on S^3 by a sequence of such contact (\pm 1)-surgeries. In the present paper, we give a shorter proof of that result and a more explicit algorithm for turning a contact r-surgery into (\pm 1)-surgeries. We use this to give explicit surgery …

Quasipositivity Problem For 3-Braids, Stepan Yu. Orevkov

Turkish Journal of Mathematics

A braid is called quasipositive if it is a product of conjugates of standard generators of the braid group. We present an algorithm deciding if a given braid with three strings is quasipositive or not. The complexity (the time of work) of our algorithm is O(n^{k+1}) where n is the length of the word in standard generators representing the braid and k is the algebraic length of the braid. The algorithm is based on the Garside normal form. The problem of quasipositivity in braid groups is motivated by the topology of plane real algebraic curves (16th Hilbert's problem). In particular, …

Solution Of The Word Problem In The Singular Braid Group, Stepan Yu. Orevkov

Turkish Journal of Mathematics

Singular braids are isotopy classes of smooth strings which are allowed to cross each other pairwise with distinct tangents. Under the usual multiplication of braids, they form a monoid. The singular braid group was introduced by Fenn-Keyman-Rourke as the quotient group of the singular braid monoid. We give a solution of the word problem for this group. It is obtained as a combination of the results by Fenn-Keyman-Rourke and some simple geometric considerations based on the mapping class interpretation of braids. Combined with Corran's normal form for the singular braid monoid, our algorithm provides a computable normal form for the …

A Combintorial Proof Of The Sum Of Q-Cubes, Kristina Garrett, Kristin Hummel

Faculty Work

We give a combinatorial proof of a q-analogue of the classical formula for the sum of cubes.