C. Baiocchi et al., INGHAM TYPE THEOREMS AND APPLICATIONS TO CONTROL-THEORY, Comptes rendus de l'Academie des sciences. Serie 1, Mathematique, 326(4), 1998, pp. 453-458
Inghanz [4] improved a previous result of Wiener [10] on nonharmonic F
ourier-series. Modifying his weight function we obtain optimal results
improving several earlier theorems of Kahane [7], Castro and Zuazua [
2] and of Jaffard Tucsnak, and Zuazua [5]. Then we apply these results
to simultaneous observability problems. (C) Academie des Sciences/Els
evier, Paris.