Talk:Schröder-Bernstein theorem/Draft: Difference between revisions

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imported>Boris Tsirelson
(4+1=five remarks)
imported>Peter Schmitt
(done)
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           \Rightarrow \sigma_\ast (S_1) \subset \sigma_\ast (S)
           \Rightarrow \sigma_\ast (S_1) \subset \sigma_\ast (S)
   </math>
   </math>
:: Oops -- correct but not what is needed. --[[User:Peter Schmitt|Peter Schmitt]] 23:37, 5 October 2010 (UTC)


"Monotone" in general may be understood as "either increasing or decreasing"; it is meant "(momotonely) increasing" or "isotone".
"Monotone" in general may be understood as "either increasing or decreasing"; it is meant "(momotonely) increasing" or "isotone".
:: Yes, that was negligent. --[[User:Peter Schmitt|Peter Schmitt]] 23:37, 5 October 2010 (UTC)


"Proof:Proof":
"Proof:Proof":
Line 20: Line 24:
: "By assumption, there are injective functions (...); they induce..."
: "By assumption, there are injective functions (...); they induce..."
because the second part of the phrase is not a part of the assumption (but its consequence).
because the second part of the phrase is not a part of the assumption (but its consequence).
:: True -- that is better. --[[User:Peter Schmitt|Peter Schmitt]] 23:37, 5 October 2010 (UTC)


"Outline": the reader can guess what is denoted by ''f'' and ''g'' (or see the details), but we'd better let him know.
"Outline": the reader can guess what is denoted by ''f'' and ''g'' (or see the details), but we'd better let him know.
:: I forgot that I did not introduce it before. --[[User:Peter Schmitt|Peter Schmitt]] 23:37, 5 October 2010 (UTC)


"Details": probably also (4) is needed, explaining what are ''A''<sub>2</sub>, ''B''<sub>1</sub> and ''B''<sub>2</sub> (which is easy) and why ''B''<sub>1</sub> is the image of ''A''<sub>1</sub> under ''f'' and ''A''<sub>2</sub> is the image of ''B''<sub>2</sub> under ''g'' (which is less easy).
"Details": probably also (4) is needed, explaining what are ''A''<sub>2</sub>, ''B''<sub>1</sub> and ''B''<sub>2</sub> (which is easy) and why ''B''<sub>1</sub> is the image of ''A''<sub>1</sub> under ''f'' and ''A''<sub>2</sub> is the image of ''B''<sub>2</sub> under ''g'' (which is less easy).


[[User:Boris Tsirelson|Boris Tsirelson]] 12:19, 5 October 2010 (UTC)
:: I was lazy -- I thought this is "obvious". --[[User:Peter Schmitt|Peter Schmitt]] 23:37, 5 October 2010 (UTC)
 
[[User:Boris Tsirelson|Boris Tsirelson]] 12:19, 5 October 2010 (UTC)
 
:: Done. Thanks. --[[User:Peter Schmitt|Peter Schmitt]] 23:37, 5 October 2010 (UTC)

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 Definition A classic theorem of set theory asserting that sets can be ordered by size. [d] [e]
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"Details": "the induced induced image"? Boris Tsirelson 06:29, 26 September 2010 (UTC)

Thanks. Corrected. --Peter Schmitt 12:26, 28 September 2010 (UTC)

"Proof:Proof":

probably should be

Oops -- correct but not what is needed. --Peter Schmitt 23:37, 5 October 2010 (UTC)

"Monotone" in general may be understood as "either increasing or decreasing"; it is meant "(momotonely) increasing" or "isotone".

Yes, that was negligent. --Peter Schmitt 23:37, 5 October 2010 (UTC)

"Proof:Proof":

"By assumption, there are injective functions (...) that induce..."

I'd say

"By assumption, there are injective functions (...); they induce..."

because the second part of the phrase is not a part of the assumption (but its consequence).

True -- that is better. --Peter Schmitt 23:37, 5 October 2010 (UTC)

"Outline": the reader can guess what is denoted by f and g (or see the details), but we'd better let him know.

I forgot that I did not introduce it before. --Peter Schmitt 23:37, 5 October 2010 (UTC)

"Details": probably also (4) is needed, explaining what are A2, B1 and B2 (which is easy) and why B1 is the image of A1 under f and A2 is the image of B2 under g (which is less easy).

I was lazy -- I thought this is "obvious". --Peter Schmitt 23:37, 5 October 2010 (UTC)

Boris Tsirelson 12:19, 5 October 2010 (UTC)

Done. Thanks. --Peter Schmitt 23:37, 5 October 2010 (UTC)