6,402 research outputs found
Natural density and probability, constructively
We give here a constructive account of the frequentist approach to
probability, by means of natural density. Using this notion of natural density,
we introduce some probabilistic versions of the Limited Principle of
Omniscience. Finally we give an attempt general definition of probability
structure which is pointfree and takes into account abstractely the process of
probability assignment
Obscure Existential Narratives: Predetermination and Freedom in Nepalese Horoscopic Knowledge.
Nepali astrological divination can be seen as a form sense-making which, in providing access to the ‘hidden motifs’ attained to determine life events, mitigates the irreducibility of being-in- the-world by providing existential narratives. Conveying hope to act upon what is initially approached as a hopeless fate, astrological knowledge forwards the perception that troubling events, apparently out of control, are also liable to be acted upon. This reveals a permanent tension between ‘fatalism’ and ‘freedom’ that challenges rendering Nepal exclusively in fatalist terms, as argued by the Nepali anthropologist Dor Bahadur Bista. Yet, accounting for these reinterpretations requires a personally-tailored inquiry, usually overlooked by sociocentric approaches that patronizingly disregard people as mere carriers of a worldview, as in the case of the ontological turn
Operads from posets and Koszul duality
We introduce a functor from the category of posets to the category
of nonsymmetric binary and quadratic operads, establishing a new connection
between these two categories. Each operad obtained by the construction provides a generalization of the associative operad because all of its
generating operations are associative. This construction has a very singular
property: the operads obtained from are almost never basic. Besides,
the properties of the obtained operads, such as Koszulity, basicity,
associative elements, realization, and dimensions, depend on combinatorial
properties of the starting posets. Among others, we show that the property of
being a forest for the Hasse diagram of the starting poset implies that the
obtained operad is Koszul. Moreover, we show that the construction
restricted to a certain family of posets with Hasse diagrams satisfying some
combinatorial properties is closed under Koszul duality.Comment: 40 page
Balanced binary trees in the Tamari lattice
We show that the set of balanced binary trees is closed by interval in the
Tamari lattice. We establish that the intervals [T0, T1] where T0 and T1 are
balanced trees are isomorphic as posets to a hypercube. We introduce tree
patterns and synchronous grammars to get a functional equation of the
generating series enumerating balanced tree intervals
A streamline derivative POD-ROM for advection-diffusion-reaction equations
We introduce a new streamline derivative projection-based closure modeling strategy for the numerical stabilization of Proper Orthogonal Decomposition-Reduced Order Models (PODROM). As a first preliminary step, the proposed model is analyzed and tested for advection-dominated advection-diffusion-reaction equations. In this framework, the numerical analysis for the Finite Element (FE) discretization of the proposed new POD-ROM is presented, by mainly deriving the corresponding error estimates. Numerical tests for advection-dominated regime show the efficiency of the proposed method, as well the increased accuracy over the standard POD-ROM that discovers its well-known limitations very soon in the numerical settings considered, i.e. for low diffusion coefficients.Nous introduisons une nouvelle stratégie de modélisation de type streamline derivative basée sur projection pour la stabilisation numérique de modèles d’ordre réduit de type POD (PODROM). Comme première étape préliminaire, le modèle proposé est analysé et testé pour les équations d’advection-diffusion-réaction dominées par l’advection. Dans ce cadre, l’analyse numérique de la discrétisation par éléments finis (FE) du nouveau POD-ROM proposé est présentée, en dérivant principalement les estimations d’erreur correspondantes. Des tests numériques pour le régime dominé par l’advection montrent l’efficacité de la méthode proposée, ainsi que la précision accrue par rapport à la méthode POD-ROM standard qui d´ecouvre très rapidement ses limites bien connues dans le cas des paramètres numériques considérés, c’est-à -dire pour de faibles coefficients de diffusion
Combinatorial operads from monoids
We introduce a functorial construction which, from a monoid, produces a
set-operad. We obtain new (symmetric or not) operads as suboperads or quotients
of the operads obtained from usual monoids such as the additive and
multiplicative monoids of integers and cyclic monoids. They involve various
familiar combinatorial objects: endofunctions, parking functions, packed words,
permutations, planar rooted trees, trees with a fixed arity, Schr\"oder trees,
Motzkin words, integer compositions, directed animals, and segmented integer
compositions. We also recover some already known (symmetric or not) operads:
the magmatic operad, the associative commutative operad, the diassociative
operad, and the triassociative operad. We provide presentations by generators
and relations of all constructed nonsymmetric operads.Comment: 42 pages. Complete version of the extended abstracts arXiv:1208.0920
and arXiv:1208.092
Constructing combinatorial operads from monoids
We introduce a functorial construction which, from a monoid, produces a
set-operad. We obtain new (symmetric or not) operads as suboperads or quotients
of the operad obtained from the additive monoid. These involve various familiar
combinatorial objects: parking functions, packed words, planar rooted trees,
generalized Dyck paths, Schr\"oder trees, Motzkin paths, integer compositions,
directed animals, etc. We also retrieve some known operads: the magmatic
operad, the commutative associative operad, and the diassociative operad.Comment: 12 page
A local-global principle for isogenies of prime degree over number fields
We give a description of the set of exceptional pairs for a number field ,
that is the set of pairs , where is a prime and is
the -invariant of an elliptic curve over which admits an
-isogeny locally almost everywhere but not globally. We obtain an upper
bound for in such pairs in terms of the degree and the discriminant of
. Moreover, we prove finiteness results about the number of exceptional
pairs.Comment: 22 pages, presentation improved as suggested by the referees. To
appear in Journal of London Mathematical Society. arXiv admin note: text
overlap with arXiv:1006.1782 by other author
When Europe encounters urban governance: Policy Types, Actor Games and Mechanisms of cites Europeanization
This paper examines European Union (EU) causal mechanisms and policy instruments affecting the urban domain throughout the lenses of the Europeanization approach. Instead of looking at EU instruments that are formally/legally consecrated to cities, we use theoretical public policy analysis to explore the arenas and the causal mechanisms that structure the encounters between the EU and urban systems of governance. Policy instruments are related to policy arenas and in turn to different mechanisms of transmission thus originating a typology of European Policy Modes. The paper focuses on four different EU instruments in the in the macro-area of sustainable development and proposes potential game-theoretical models for each of them.
In the conclusions we highlight the differences between this approach and the traditional analysis of EU urban policy, and suggest avenues for future empirical research based on typologies of policy instruments and modes of Europeanization
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