no code implementations • 10 Nov 2023 • Amir Ali Ahmadi, Abraar Chaudhry, Jeffrey Zhang
At each step, our $d^{\text{th}}$-order method uses semidefinite programming to construct and minimize a sum of squares-convex approximation to the $d^{\text{th}}$-order Taylor expansion of the function we wish to minimize.
no code implementations • 20 May 2023 • Amir Ali Ahmadi, Abraar Chaudhry, Vikas Sindhwani, Stephen Tu
For $T=2$, we give a semidefinite representation of the set of safe initial conditions and show that $\lceil n/2 \rceil$ trajectories generically suffice for safe learning.
no code implementations • 11 May 2021 • Amir Ali Ahmadi, Cemil Dibek, Georgina Hall
We establish that the answer to question (i) is positive for univariate plus quadratic polynomials and for convex SPQ polynomials, but negative already for bivariate quartic SPQ polynomials.
no code implementations • 24 Nov 2020 • Amir Ali Ahmadi, Abraar Chaudhry, Vikas Sindhwani, Stephen Tu
For our first two results, we consider the setting of safely learning linear dynamics.
1 code implementation • L4DC 2020 • Amir Ali Ahmadi, Bachir El Khadir
We then demonstrate the added value of side information for learning the dynamics of basic models in physics and cell biology, as well as for learning and controlling the dynamics of a model in epidemiology.
no code implementations • 14 Aug 2020 • Amir Ali Ahmadi, Jeffrey Zhang
We consider the notions of (i) critical points, (ii) second-order points, (iii) local minima, and (iv) strict local minima for multivariate polynomials.
no code implementations • 12 Aug 2020 • Amir Ali Ahmadi, Jeffrey Zhang
We show that unless P=NP, there cannot be a polynomial-time algorithm that finds a point within Euclidean distance $c^n$ (for any constant $c \ge 0$) of a local minimizer of an $n$-variate quadratic function over a polytope.
no code implementations • 14 Aug 2019 • Anirudha Majumdar, Georgina Hall, Amir Ali Ahmadi
Historically, scalability has been a major challenge to the successful application of semidefinite programming in fields such as machine learning, control, and robotics.
no code implementations • 16 Jun 2018 • Amir Ali Ahmadi, Georgina Hall
As a byproduct, our proof shows that the problem of testing whether all matrices in an interval family are positive semidefinite is strongly NP-hard.
no code implementations • 9 Oct 2017 • Amir Ali Ahmadi, Anirudha Majumdar
In a recent note [8], the author provides a counterexample to the global convergence of what his work refers to as "the DSOS and SDSOS hierarchies" for polynomial optimization problems (POPs) and purports that this refutes claims in our extended abstract [4] and slides in [3].
no code implementations • 8 Jun 2017 • Amir Ali Ahmadi, Anirudha Majumdar
The reliance of this technique on large-scale semidefinite programs however, has limited the scale of problems to which it can be applied.
no code implementations • 22 Nov 2016 • Amir Ali Ahmadi, Georgina Hall, Ameesh Makadia, Vikas Sindhwani
Motivated by applications in robotics and computer vision, we study problems related to spatial reasoning of a 3D environment using sublevel sets of polynomials.
no code implementations • 6 Oct 2015 • Amir Ali Ahmadi, Georgina Hall
We consider the problem of decomposing a multivariate polynomial as the difference of two convex polynomials.