Can you please clarify the question? What do you mean by "adjoint operator"? It looks like you are actually studying self-adjoint operators. Also, when you say closed, are you talking about operator norm topology? Are you working on a Banach space, Hilbert space, something else? —
Nate Eldredge 12 mins ago
The set of all adjoint operators are closed in Hilbert space.
We are working with the operator norm.
An operator $T$ is said to self-adjoint if $T = T^*$ where $T^*$ is the adjoint of operator $T$.
To prove the above statement let us consider a sequence of adjoint operators $\{T_{n}\}$ conver...
