Null Controllability for Degenerate Parabolic Operators

the null controllability problemwant to study null-controllability in time T > 0∀u 0 ∈ L 2 (O) ∃f ∈ L 2 (Q T ) :{u f (·, T ) ≡ 0∫Q T|f | 2 ≤ C T∫O |u 0| 2uniformly parabolic equations∃ m > 0 : A(x) ≥ m I n =⇒ null-controllability ∀ T > 0• Fattorini and Russell (1971), Russell (1978)• Lebeau and Robbiano (1995)• Fursikov and Emanouilov (1996)• Tataru (1997)