Now showing items 1-9 of 9

• #### Abstract Bivariant Cuntz Semigroups ﻿

[OWP-2017-04] (Mathematisches Forschungsinstitut Oberwolfach, 2017-02-13)
We show that abstract Cuntz semigroups form a closed symmetric monoidal category. Thus, given Cuntz semigroups $S$ and $T$, there is another Cuntz semigroup $((S,T))$ playing the role of morphisms from $S$ to $T$. Applied ...
• #### Dominance and Transmissions in Supertropical Valuation Theory ﻿

[OWP-2011-07] (Mathematisches Forschungsinstitut Oberwolfach, 2011)
This paper is a sequel of [IKR1], where we defined supervaluations on a commutative ring $R$ and studied a dominance relation $\Phi >= v$ between supervaluations $\varphi$ and $\upsilon$ on $R$, aiming at an enrichment of ...
• #### 1240c - Mini-Workshop: Cohomology Rings and Fundamental Groups of Hyperplane Arrangements, Wonderful Compactifications, and Real Toric Varieties ﻿

[OWR-2012-49] (2012) - (01 Oct - 06 Oct 2012)
The purpose of this workshop was to bring together researchers with a common interest in the objects mentioned in the title from, respectively, the points of view of toric and tropical geometry, arrangement theory, and ...
• #### 1651c - Mini-Workshop: Surreal Numbers, Surreal Analysis, Hahn Fields and Derivations ﻿

[OWR-2016-60] (2016) - (18 Dec - 23 Dec 2016)
New striking analogies between H. Hahn’s fields of generalised series with real coefficients, G. H. Hardy’s field of germs of real valued functions, and J. H. Conway’s field No of surreal numbers, have been lately discovered ...
• #### Monoid valuations and value ordered supervaluations ﻿

[OWP-2011-17] (Mathematisches Forschungsinstitut Oberwolfach, 2011)
We complement two papers on supertropical valuation theory ([IKR1], [IKR2]) by providing natural examples of m-valuations (= monoid valuations), after that of supervaluations and transmissions between them. The supervaluations ...
• #### New representations of matroids and generalizations ﻿

[OWP-2011-18] (Mathematisches Forschungsinstitut Oberwolfach, 2011)
We extend the notion of matroid representations by matrices over fields by considering new representations of matroids by matrices over finite semirings, more precisely over the boolean and the superboolean semirings. This ...
• #### 0732 - Permutation Groups ﻿

[OWR-2007-37] (2007) - (05 Aug - 11 Aug 2007)
Abstract. The theory of permutation groups is essentially the theory of symmetry for mathematical and physical systems, and therefore has major impact in diverse areas of mathematics. Recent significant advances in permutation ...
• #### 1818 - Quadratic Forms and Related Structures over Fields ﻿

[OWR-2018-21] (2018) - (29 Apr - 05 May 2018)
The range of topics discussed at the workshop “Quadratic Forms and Related Structures over Fields” included core themes from the algebraic theory of quadratic and hermitian forms and their Witt groups, several aspects of ...
• #### Supertropical semirings and supervaluations ﻿

[OWP-2010-05] (Mathematisches Forschungsinstitut Oberwolfach, 2010)
We interpret a valuation $\upsilon$ on a ring $R$ as a map $\upsilon:R \rightarrow M$ into a so called bipotent semiring $M$ (the usual max-plus setting), and then define a supervaluation $\varphi$ as a suitable map into ...