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answered Largest “leap-to-generality” in math history?
Nov
15
revised right inverse and supplement of kernel in a banach
added 2 characters in body
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
15
revised right inverse and supplement of kernel in a banach
edited title
Nov
15
asked right inverse and supplement of kernel in a banach
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
11
answered How to show that $(\operatorname{Im}{A})^⊥ = \ker(A^⊤)$, $\operatorname{Im}{(A^⊤)}= (\ker A)^⊥$?
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
Nov
8
awarded  Yearling
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
awarded  Notable Question