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visits member for 2 years, 8 months
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Nov
15
comment right inverse and supplement of kernel in a banach
oh yes, sorry. I'll fix that
Nov
15
comment right inverse and supplement of kernel in a banach
it sounds like a more elegant formulation.
Nov
13
comment If $f$ is continuous at $a$, is it continuous in some open interval around $a$?
@Kaz what do you mean ?
Nov
12
comment How to show that $(\operatorname{Im}{A})^⊥ = \ker(A^⊤)$, $\operatorname{Im}{(A^⊤)}= (\ker A)^⊥$?
in infinite dimension, one only has $closure(Im A^T) \subset {ker A}^\perp$
Nov
11
comment show: $\overline{\overline X} = \overline X$
this is the way to prove it. dealing with epsilon is overkill for this
Nov
11
comment How to show that $(\operatorname{Im}{A})^⊥ = \ker(A^⊤)$, $\operatorname{Im}{(A^⊤)}= (\ker A)^⊥$?
@Timbuc he refers to another question I think
Nov
11
comment How to show that $(\operatorname{Im}{A})^⊥ = \ker(A^⊤)$, $\operatorname{Im}{(A^⊤)}= (\ker A)^⊥$?
@qexi this is another question. and one for which you might be surprised by the answer :)
Nov
11
comment How to show that $(\operatorname{Im}{A})^⊥ = \ker(A^⊤)$, $\operatorname{Im}{(A^⊤)}= (\ker A)^⊥$?
this is not always true in infinite dimension I think btw
Nov
10
comment Can't argue with success? Looking for “bad math” that “gets away with it”
That was a test by the student to see if teacher reads the proof
Nov
10
comment Can't argue with success? Looking for “bad math” that “gets away with it”
@joriki if only mathematics was using "expressions", binders, higher order functions, and other rigorous CS notations (de brujin), the work would be a better place.. how many bad conceptual math have been produced by wrong notations...
Nov
10
comment Can't argue with success? Looking for “bad math” that “gets away with it”
@Squirtle I just did
Nov
10
comment Can't argue with success? Looking for “bad math” that “gets away with it”
@GrumpyParsnip that counts as luck in my book
Oct
30
comment A finite group of even order has an odd number of elements of order 2
you know what, that was annoying. so easy after seeing it it is fuming.
Oct
18
comment Does $1.0000000000\cdots 1$ with an infinite number of $0$ in it exist?
I fail to see the connection of automaton with the problem at hand..
Oct
18
comment Does $1.0000000000\cdots 1$ with an infinite number of $0$ in it exist?
thanks for mentioning non standard analysis. that is what physicists are using everyday...
Oct
16
comment Past Papers Of multivariable calculus OF MIT,Princeton or harvard
at the teacher office
Apr
13
comment How to prove and interpret $\operatorname{rank}(AB) \leq \operatorname{min}(\operatorname{rank}(A), \operatorname{rank}(B))$?
I am not familiar with the 'categorification'. How can one go from this to the rank inequality ? What functor is to be applied ?
Apr
11
comment function application order
i think you are right about the conclusion. it is the convention of most textbook, so i better suck it up. i notice that lawvere uses the natural order though !(tac.mta.ca/tac/reprints/articles/16/tr16.pdf)
Mar
21
comment If $g \circ f$ is monic, then $f$ is monic
Amazing answer.....
Mar
19
comment How to prove hom functor preserves pullbacks
@user43687 yes this is more powerful, although I quite like to have the direct proof as well.