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Solubility of Systems of Quadratic Forms [PDF]

open access: yesBulletin of the London Mathematical Society, 1997
We derive an upper bound for the least number of variables needed to guarantee that a system of t quadratic forms (t>=2) over a field F has a nontrivial zero. In particular, if F is a local field, then 2t^2+3 variables insure the existence of a nontrivial zero (2t^2+1 if t is even), while if F=Q_p with p>=11, then 2t^2-2t+5 variables suffice (2t ...
Martin, Greg
openaire   +6 more sources

Representations of integers by systems of three quadratic forms [PDF]

open access: yesProceedings of the London Mathematical Society, 2016
64 pages, minor edits to exposition to agree with published ...
Pierce, Lillian B.   +2 more
core   +7 more sources

Zeros of Systems of ${\mathfrak p}$-adic Quadratic Forms

open access: yes, 2008
Revised version, with better treatment and results for characteristic ...
Heath-Brown, D. R.
openaire   +5 more sources

On an oppenheim-type conjecture for systems of quadratic forms

open access: yesIsrael Journal of Mathematics, 2004
Let Q_i, i=1,...,t, be real nondegenerate indefinite quadratic forms in d variables. We investigate under what conditions the closure of the set {(Q_1(x),...,Q_t(x)): x\in Z^d-{0}} contains (0,..,0). As a corollary, we deduce several results on the magnitude of the set of g\in GL(d,R) such that the closure of the set {(Q_1(gx),...,Q_t(gx)): x\in Z^d-{
Gorodnik, Alexander
openaire   +3 more sources

Effective Lagrangian for Nonrelativistic Systems

open access: yesPhysical Review X, 2014
The effective Lagrangian for Nambu-Goldstone bosons (NGBs) in systems without Lorentz invariance has a novel feature that some of the NGBs are canonically conjugate to each other, hence describing 1 dynamical degree of freedom by two NGB fields.
Haruki Watanabe, Hitoshi Murayama
doaj   +3 more sources

Quadratic Theory of Gravity with a Scalar Field and Type I Shapovalov Wave Spacetimes

open access: yesUniverse, 2022
For the quadratic theory of gravity with a scalar field, exact solutions are found for gravitational-wave models in Shapovalov I-type spacetimes, which do not arise in models of the general theory of relativity.
Konstantin Osetrin   +2 more
doaj   +1 more source

Systems of Hermitian Quadratic Forms [PDF]

open access: yesCanadian Mathematical Bulletin, 2004
AbstractIn this paper, we give some conditions to judge when a system of Hermitian quadratic forms has a real linear combination which is positive definite or positive semi-definite. We also study some related geometric and topological properties of the moduli space.
Ma, Li, Chen, Dezhong
openaire   +1 more source

Geometry, integrability and bifurcation diagrams of a family of quadratic differential systems as application of the Darboux theory of integrability

open access: yesElectronic Journal of Qualitative Theory of Differential Equations, 2021
During the last forty years the theory of integrability of Darboux, in terms of algebraic invariant curves of polynomial systems has been very much extended and it is now an active area of research.
Regilene Oliveira   +3 more
doaj   +1 more source

Characterization of Positive Invariance of Quadratic Convex Sets for Discrete-Time Systems Using Optimization Approaches

open access: yesMathematics, 2023
A positively invariant set is an important concept in dynamical systems. The study of positively invariant set conditions for discrete-time systems is one interesting topic in both theoretical studies and practical applications research.
Yuyao Lei   +2 more
doaj   +1 more source

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