What is the condition in unbounded oprerators?

[smati]

Homework Statement

T₁, T₂ and T₃ are unbounded operators.

What is this condition?
http://T[SUB]1[/SUB]
3. The Attempt at a Solution [/B]
T₂ is the identity operator and D(T₃)⊂D(T₁) / D is the domain of definition.

 

[smati]

Homework Statement

T₁, T₂ and T₃ are unbounded operators.

What is this condition?
http://T[SUB]1[/SUB]
3. The Attempt at a Solution [/B]
https://scontent-mrs1-1.xx.fbcdn.net/t31.0-8/13958240_283354382042877_6744203050697608959_o.jpg