159 reputation
9
bio website
location
age
visits member for 3 years, 9 months
seen Oct 27 at 7:52

Oct
2
awarded  Commentator
Oct
2
comment Tensor product of operators
Should not the last expression be of the similar form as for vectors, i.e. $T=\sum_i \sum_j c_{ij} T_{1,i} \otimes T_{2,j}$?
Sep
25
awarded  Popular Question
Dec
10
awarded  Citizen Patrol
Dec
1
comment Inner product for vector space over arbitrary field
Hmmm... I think the requirement that the field should be ordered is a bit too strict and it obviously won't even work for complex vector spaces. A presence of an ordered subfield in the field should be enough as in the case of a complex vector space, where the inner product is defined in such a way that it always returns the value from the field of real numbers (which is an ordered subfield of the field of complex numbers) when both arguments are the same.
Nov
15
accepted What is the null vector for the vector space of continuous functions $f \colon \mathbf{R} \to \mathbf{C}$?
Nov
15
comment What is the null vector for the vector space of continuous functions $f \colon \mathbf{R} \to \mathbf{C}$?
Just a quick follow-up that came into my head right now: strictly speaking is it also true for $L^2$? Or there is something funny with the "Lebesgue measure zero" as in the case of the equivalence of two functions? I don't know what this "Lebesgue measure zero" actually is, but I just read that two functions on $L^2$ are considered to be equivalent if the are equal everywhere except on a subset of the real numbers that have this "Lebesgue measure zero" (whatever it is).
Nov
15
asked What is the null vector for the vector space of continuous functions $f \colon \mathbf{R} \to \mathbf{C}$?
Sep
1
awarded  Critic
Jun
3
comment Distinguishing between symmetric, Hermitian and self-adjoint operators
@leslietownes thanks for the reference! ;) So it was Friedrichs who met Heisenberg, not von Neumann himself, and this story is not an anecdote.
Jun
3
comment Distinguishing between symmetric, Hermitian and self-adjoint operators
Hmmm... Self-adjoint implies symmetric by definition. But how do we know that Hermitian implies self-adjoint?
Apr
23
comment Is there any standard notation for specifying dimension of a matrix after the matrix symbol?
@Arkamis Of course. That's how we use parentheses to resolve ambiguities. You're right. Thanks. :)
Apr
23
comment Is there any standard notation for specifying dimension of a matrix after the matrix symbol?
@Arkamis But I want to specify the dimension of conjugate transpose matrix, not the initial matrix.
Apr
23
comment Is there any standard notation for specifying dimension of a matrix after the matrix symbol?
@Arkamis This notation can be ambiguous. I've updated my question to show a specific example when this is the case.
Apr
23
revised Is there any standard notation for specifying dimension of a matrix after the matrix symbol?
added 730 characters in body
Apr
23
asked Is there any standard notation for specifying dimension of a matrix after the matrix symbol?
Mar
7
awarded  Editor
Mar
7
revised Ideas for denoting parameters of a function, as opposed to variables, in the list of arguments?
added 81 characters in body
Mar
6
asked Ideas for denoting parameters of a function, as opposed to variables, in the list of arguments?
Mar
1
comment What's the difference between tuples and sequences?
This caught us by surprise today. There are no strict defenitions? :O Really? Usually, by convention. Sounds weird for mathematics. Seems like we just have two terms for one thing and a convention... Occam's razor to the rescue!