# American Institute of Mathematical Sciences

2016, 10: 331-338. doi: 10.3934/jmd.2016.10.331

## An Urysohn-type theorem under a dynamical constraint

 1 UMPA, ENS-Lyon, 46 allée d’Italie, 69364 Lyon Cedex 7, France

Received  January 2016 Revised  June 2016 Published  July 2016

We address the following question raised by M. Entov and L. Polterovich: given a continuous map $f:X\to X$ of a metric space $X$, closed subsets $A,B\subset X$, and an integer $n\geq 1$, when is it possible to find a continuous function $\theta:X\to\mathbb{R}$ such that $\theta f-\theta\leq 1, \quad \theta|A\leq 0, \quad\text{and}\quad \theta|B> n\,?$ To keep things as simple as possible, we solve the problem when $A$ is compact. The non-compact case will be treated in a later work.
Citation: Albert Fathi. An Urysohn-type theorem under a dynamical constraint. Journal of Modern Dynamics, 2016, 10: 331-338. doi: 10.3934/jmd.2016.10.331
##### References:
 [1] L. Buhovsky, M. Entov and L. Polterovich, Poisson brackets and symplectic invariants,, Selecta Math. (N.S.), 18 (2012), 89.  doi: 10.1007/s00029-011-0068-9.  Google Scholar [2] M. Entov and L. Polterovich, Lagrangian tetragons and instabilities in Hamiltonian dynamics,, , ().   Google Scholar [3] A. Fathi and P. Pageault, Aubry-Mather theory for homeomorphisms,, Ergodic Theory Dynam. Systems, 35 (2015), 1187.  doi: 10.1017/etds.2013.107.  Google Scholar [4] J. L. Kelley, General Topology,, Graduate Texts in Mathematics, (1975).   Google Scholar

show all references

##### References:
 [1] L. Buhovsky, M. Entov and L. Polterovich, Poisson brackets and symplectic invariants,, Selecta Math. (N.S.), 18 (2012), 89.  doi: 10.1007/s00029-011-0068-9.  Google Scholar [2] M. Entov and L. Polterovich, Lagrangian tetragons and instabilities in Hamiltonian dynamics,, , ().   Google Scholar [3] A. Fathi and P. Pageault, Aubry-Mather theory for homeomorphisms,, Ergodic Theory Dynam. Systems, 35 (2015), 1187.  doi: 10.1017/etds.2013.107.  Google Scholar [4] J. L. Kelley, General Topology,, Graduate Texts in Mathematics, (1975).   Google Scholar
 [1] Jie Zhang, Yuping Duan, Yue Lu, Michael K. Ng, Huibin Chang. Bilinear constraint based ADMM for mixed Poisson-Gaussian noise removal. Inverse Problems & Imaging, , () : -. doi: 10.3934/ipi.2020071

2019 Impact Factor: 0.465