Project acronym FLIRT
Project Fluid Flows and Irregular Transport
Researcher (PI) Gianluca Crippa
Host Institution (HI) UNIVERSITAT BASEL
Call Details Starting Grant (StG), PE1, ERC-2015-STG
Summary "Several important partial differential equations (PDEs) arising in the mathematical description of physical phenomena exhibit transport features: physical quantities are advected by velocity fields that drive the dynamics of the system. This is the case for instance for the Euler equation of fluid dynamics, for conservation laws, and for kinetic equations.
An ubiquitous feature of these phenomena is their intrinsic lack of regularity. From the mathematical point of view this stems from the nonlinearity and/or nonlocality of the PDEs. Moreover, the lack of regularity also encodes actual properties of the underlying physical systems: conservation laws develop shocks (discontinuities that propagate in time), solutions to the Euler equation exhibit rough and ""disordered"" behaviors. This irregularity is the major difficulty in the mathematical analysis of such problems, since it prevents the use of many standard methods, foremost the classical (and powerful) theory of characteristics.
For these reasons, the study in a non smooth setting of transport and continuity equations, and of flows of ordinary differential equations, is a fundamental tool to approach challenging important questions concerning these PDEs.
This project aims at establishing:
(1) deep insight into the structure of solutions of nonlinear PDEs, in particular the Euler equation and multidimensional systems of conservation laws,
(2) rigorous bounds for mixing phenomena in fluid flows, phenomena for which giving a precise mathematical formulation is extremely challenging.
The unifying factor of this proposal is that the analysis will rely on major advances in the theory of flows of ordinary differential equations in a non smooth setting, thus providing a robust formulation via characteristics for the PDEs under consideration. The guiding thread is the crucial role of geometric measure theory techniques, which are extremely efficient to describe and investigate irregular phenomena."
Summary
"Several important partial differential equations (PDEs) arising in the mathematical description of physical phenomena exhibit transport features: physical quantities are advected by velocity fields that drive the dynamics of the system. This is the case for instance for the Euler equation of fluid dynamics, for conservation laws, and for kinetic equations.
An ubiquitous feature of these phenomena is their intrinsic lack of regularity. From the mathematical point of view this stems from the nonlinearity and/or nonlocality of the PDEs. Moreover, the lack of regularity also encodes actual properties of the underlying physical systems: conservation laws develop shocks (discontinuities that propagate in time), solutions to the Euler equation exhibit rough and ""disordered"" behaviors. This irregularity is the major difficulty in the mathematical analysis of such problems, since it prevents the use of many standard methods, foremost the classical (and powerful) theory of characteristics.
For these reasons, the study in a non smooth setting of transport and continuity equations, and of flows of ordinary differential equations, is a fundamental tool to approach challenging important questions concerning these PDEs.
This project aims at establishing:
(1) deep insight into the structure of solutions of nonlinear PDEs, in particular the Euler equation and multidimensional systems of conservation laws,
(2) rigorous bounds for mixing phenomena in fluid flows, phenomena for which giving a precise mathematical formulation is extremely challenging.
The unifying factor of this proposal is that the analysis will rely on major advances in the theory of flows of ordinary differential equations in a non smooth setting, thus providing a robust formulation via characteristics for the PDEs under consideration. The guiding thread is the crucial role of geometric measure theory techniques, which are extremely efficient to describe and investigate irregular phenomena."
Max ERC Funding
1 009 351 €
Duration
Start date: 2016-06-01, End date: 2021-05-31
Project acronym GRAPHCPX
Project A graph complex valued field theory
Researcher (PI) Thomas Hans Willwacher
Host Institution (HI) EIDGENOESSISCHE TECHNISCHE HOCHSCHULE ZUERICH
Call Details Starting Grant (StG), PE1, ERC-2015-STG
Summary The goal of the proposed project is to create a universal (AKSZ type) topological field theory with values in graph complexes, capturing the rational homotopy types of manifolds, configuration and embedding spaces.
If successful, such a theory will unite certain areas of mathematical physics, topology, homological algebra and algebraic geometry. More concretely, from the physical viewpoint it would give a precise topological interpretation of a class of well studied topological field theories, as opposed to the current state of the art, in which these theories are defined by giving formulae without guarantees on the non-triviality of the produced invariants.
From the topological viewpoint such a theory will provide new tools to study much sought after objects like configuration and embedding spaces, and tentatively also diffeomorphism groups, through small combinatorial models given by Feynman diagrams. In particular, this will unite and extend existing graphical models of configuration and embedding spaces due to Kontsevich, Lambrechts, Volic, Arone, Turchin and others.
From the homological algebra viewpoint a field theory as above provides a wealth of additional algebraic structures on the graph complexes, which are some of the most central and most mysterious objects in the field.
Such algebraic structures are expected to yield constraints on the graph cohomology, as well as ways to construct series of previously unknown classes.
Summary
The goal of the proposed project is to create a universal (AKSZ type) topological field theory with values in graph complexes, capturing the rational homotopy types of manifolds, configuration and embedding spaces.
If successful, such a theory will unite certain areas of mathematical physics, topology, homological algebra and algebraic geometry. More concretely, from the physical viewpoint it would give a precise topological interpretation of a class of well studied topological field theories, as opposed to the current state of the art, in which these theories are defined by giving formulae without guarantees on the non-triviality of the produced invariants.
From the topological viewpoint such a theory will provide new tools to study much sought after objects like configuration and embedding spaces, and tentatively also diffeomorphism groups, through small combinatorial models given by Feynman diagrams. In particular, this will unite and extend existing graphical models of configuration and embedding spaces due to Kontsevich, Lambrechts, Volic, Arone, Turchin and others.
From the homological algebra viewpoint a field theory as above provides a wealth of additional algebraic structures on the graph complexes, which are some of the most central and most mysterious objects in the field.
Such algebraic structures are expected to yield constraints on the graph cohomology, as well as ways to construct series of previously unknown classes.
Max ERC Funding
1 162 500 €
Duration
Start date: 2016-07-01, End date: 2021-06-30
Project acronym POLYTE
Project Polynomial term structure models
Researcher (PI) Damir Filipovic
Host Institution (HI) ECOLE POLYTECHNIQUE FEDERALE DE LAUSANNE
Call Details Starting Grant (StG), PE1, ERC-2012-StG_20111012
Summary "The term structure of interest rates plays a central role in the functioning of the interbank market. It also represents a key factor for the valuation and management of long term liabilities, such as pensions. The financial crisis has revealed the multivariate risk nature of the term structure, which includes inflation, credit and liquidity risk, resulting in multiple spread adjusted discount curves. This has generated a strong interest in tractable stochastic models for the movements of the term structure that can match all determining risk factors.
We propose a new class of term structure models based on polynomial factor processes which are defined as jump-diffusions whose generator leaves the space of polynomials of any fixed degree invariant. The moments of their transition distributions are polynomials in the initial state. The coefficients defining this relationship are given as solutions of a system of nested linear ordinary differential equations. As a consequence polynomial processes yield closed form polynomial-rational expressions for the term structure of interest rates. Polynomial processes include affine processes, whose transition functions admit an exponential-affine characteristic function. Affine processes are among the most widely used models in finance to date, but come along with some severe specification limitations. We propose to overcome these shortcomings by studying polynomial processes and polynomial expansion methods achieving a comparable efficiency as Fourier methods in the affine case.
In sum, the objectives of this project are threefold. First, we plan to develop a theory for polynomial processes and entirely explore their statistical properties. This fills a gap in the literature on affine processes in particular. Second, we aim to develop polynomial-rational term structure models addressing the new paradigm of multiple spread adjusted discount curves. Third, we plan to implement and estimate these models using real market data."
Summary
"The term structure of interest rates plays a central role in the functioning of the interbank market. It also represents a key factor for the valuation and management of long term liabilities, such as pensions. The financial crisis has revealed the multivariate risk nature of the term structure, which includes inflation, credit and liquidity risk, resulting in multiple spread adjusted discount curves. This has generated a strong interest in tractable stochastic models for the movements of the term structure that can match all determining risk factors.
We propose a new class of term structure models based on polynomial factor processes which are defined as jump-diffusions whose generator leaves the space of polynomials of any fixed degree invariant. The moments of their transition distributions are polynomials in the initial state. The coefficients defining this relationship are given as solutions of a system of nested linear ordinary differential equations. As a consequence polynomial processes yield closed form polynomial-rational expressions for the term structure of interest rates. Polynomial processes include affine processes, whose transition functions admit an exponential-affine characteristic function. Affine processes are among the most widely used models in finance to date, but come along with some severe specification limitations. We propose to overcome these shortcomings by studying polynomial processes and polynomial expansion methods achieving a comparable efficiency as Fourier methods in the affine case.
In sum, the objectives of this project are threefold. First, we plan to develop a theory for polynomial processes and entirely explore their statistical properties. This fills a gap in the literature on affine processes in particular. Second, we aim to develop polynomial-rational term structure models addressing the new paradigm of multiple spread adjusted discount curves. Third, we plan to implement and estimate these models using real market data."
Max ERC Funding
995 155 €
Duration
Start date: 2012-12-01, End date: 2017-11-30
Project acronym RAM
Project Regularity theory for area minimizing currents
Researcher (PI) Camillo De Lellis
Host Institution (HI) UNIVERSITAT ZURICH
Call Details Starting Grant (StG), PE1, ERC-2012-StG_20111012
Summary "The Plateau's problem consists in finding the surface of least area spanning a given contour. This question has attracted the attention of many mathematicians in the last two centuries, providing a prototypical problem for several fields of research in mathematics. For hypersurfaces a lot is known about the existence and regularity thanks to the classical works of De Giorgi, Almgren, Fleming, Federer, Simons, Allard, Simon, Schoen and several other authors.
In higher codimension a quite powerful existence theory, the ``theory of currents'', was developed by Federer and Fleming in 1960. The success of this theory relies on its homological flavor and indeed it has found several applications to problems in differential geometry. Many geometric objects which are widely studied in the modern literature are naturally area-minimizing currents: two examples among many are special lagrangians and holomorphic subvarieties. However the understanding of the regularity issues is, compared to the case of hypersurfaces, much poorer. Aside from its intrinsic interest, a good regularity theory is likely to provide more insightful geometric applications. A quite striking example is Taubes' proof of the equivalence between the Gromov and Seiberg-Witten invariants.
A very complicated and far reaching regularity theory has been developed by Almgren thirty years ago in a monumental work of almost 1000 pages. The first part of this project aims at reaching the same conclusions of Almgren with a more flexible and accessible theory. In the second part I wish to go beyond Almgren's work and attack some of the many open questions which still remain in the field."
Summary
"The Plateau's problem consists in finding the surface of least area spanning a given contour. This question has attracted the attention of many mathematicians in the last two centuries, providing a prototypical problem for several fields of research in mathematics. For hypersurfaces a lot is known about the existence and regularity thanks to the classical works of De Giorgi, Almgren, Fleming, Federer, Simons, Allard, Simon, Schoen and several other authors.
In higher codimension a quite powerful existence theory, the ``theory of currents'', was developed by Federer and Fleming in 1960. The success of this theory relies on its homological flavor and indeed it has found several applications to problems in differential geometry. Many geometric objects which are widely studied in the modern literature are naturally area-minimizing currents: two examples among many are special lagrangians and holomorphic subvarieties. However the understanding of the regularity issues is, compared to the case of hypersurfaces, much poorer. Aside from its intrinsic interest, a good regularity theory is likely to provide more insightful geometric applications. A quite striking example is Taubes' proof of the equivalence between the Gromov and Seiberg-Witten invariants.
A very complicated and far reaching regularity theory has been developed by Almgren thirty years ago in a monumental work of almost 1000 pages. The first part of this project aims at reaching the same conclusions of Almgren with a more flexible and accessible theory. In the second part I wish to go beyond Almgren's work and attack some of the many open questions which still remain in the field."
Max ERC Funding
919 500 €
Duration
Start date: 2012-09-01, End date: 2017-08-31
Project acronym SPARCCLE
Project STRUCTURE PRESERVING APPROXIMATIONS FOR ROBUST COMPUTATION OF CONSERVATION LAWS AND RELATED EQUATIONS
Researcher (PI) Siddhartha Mishra
Host Institution (HI) EIDGENOESSISCHE TECHNISCHE HOCHSCHULE ZUERICH
Call Details Starting Grant (StG), PE1, ERC-2012-StG_20111012
Summary "Many interesting systems in physics and engineering are mathematically modeled by first-order non-linear hyperbolic partial differential equations termed as systems of conservation laws. Examples include the Euler equations of aerodynamics, the shallow water equations of oceanography, multi-phase flows in a porous medium (used in the oil industry), equations of non-linear elasticity and the MHD equations of plasma physics. Numerical methods are the key tools to study these equations and to simulate interesting phenomena such as shock waves.
Despite the intense development of numerical methods for the past three decades and great success in applying these methods to large scale complex physical and engineering simulations, the massive increase in computational power in recent years has exposed the inability of state of the art schemes to simulate very large, multiscale, multiphysics three dimensional problems on complex geometries. In particular, problems with strong shocks that depend explicitly on underlying small scale effects, involve geometric constraints like vorticity and require uncertain inputs such as random initial data and source terms, are beyond the range of existing methods.
The main goal of this project will be to design space-time adaptive \emph{structure preserving} arbitrarily high-order finite volume and discontinuous Galerkin schemes that incorporate correct small scale information and provide for efficient uncertainty quantification. These schemes will tackle emerging grand challenges and dramatically increase the range and scope of numerical simulations for systems modeled by hyperbolic PDEs. Moreover, the schemes will be implemented to ensure optimal performance on emerging massively parallel hardware architecture. The resulting publicly available code can be used by scientists and engineers to study complex systems and design new technologies."
Summary
"Many interesting systems in physics and engineering are mathematically modeled by first-order non-linear hyperbolic partial differential equations termed as systems of conservation laws. Examples include the Euler equations of aerodynamics, the shallow water equations of oceanography, multi-phase flows in a porous medium (used in the oil industry), equations of non-linear elasticity and the MHD equations of plasma physics. Numerical methods are the key tools to study these equations and to simulate interesting phenomena such as shock waves.
Despite the intense development of numerical methods for the past three decades and great success in applying these methods to large scale complex physical and engineering simulations, the massive increase in computational power in recent years has exposed the inability of state of the art schemes to simulate very large, multiscale, multiphysics three dimensional problems on complex geometries. In particular, problems with strong shocks that depend explicitly on underlying small scale effects, involve geometric constraints like vorticity and require uncertain inputs such as random initial data and source terms, are beyond the range of existing methods.
The main goal of this project will be to design space-time adaptive \emph{structure preserving} arbitrarily high-order finite volume and discontinuous Galerkin schemes that incorporate correct small scale information and provide for efficient uncertainty quantification. These schemes will tackle emerging grand challenges and dramatically increase the range and scope of numerical simulations for systems modeled by hyperbolic PDEs. Moreover, the schemes will be implemented to ensure optimal performance on emerging massively parallel hardware architecture. The resulting publicly available code can be used by scientists and engineers to study complex systems and design new technologies."
Max ERC Funding
1 220 433 €
Duration
Start date: 2012-12-01, End date: 2017-11-30
