Infinite descendant sequences












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$begingroup$


"Show that the order $(A,<)$ is well ordering if and only if there no exists infinite descendant sequences in $A$".



Can you help me whit this problem, please, what happens is that my professor isn't gave us the definition of "infinite descendant sequences", so i haven't enough basis to solve this problem.



Thanks.










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$endgroup$












  • $begingroup$
    can you specify your definition of well.ordering.
    $endgroup$
    – J.F
    Jan 18 at 23:28










  • $begingroup$
    A set $A$ is well ordering if all no-empty subset of $A$ have a minimum element.
    $endgroup$
    – Lennis Mariana
    Jan 18 at 23:31










  • $begingroup$
    A very standard equivalent one (which is i guess the thing you have to prove) is the following : Every decreasing sequence of elements of $A$ must be finite.
    $endgroup$
    – J.F
    Jan 18 at 23:36












  • $begingroup$
    Ok, i think i have the idea, i'll try to prove in this way, thanks.
    $endgroup$
    – Lennis Mariana
    Jan 18 at 23:45










  • $begingroup$
    I can put this as an answer to close the question if you want.
    $endgroup$
    – J.F
    Jan 18 at 23:46
















0












$begingroup$


"Show that the order $(A,<)$ is well ordering if and only if there no exists infinite descendant sequences in $A$".



Can you help me whit this problem, please, what happens is that my professor isn't gave us the definition of "infinite descendant sequences", so i haven't enough basis to solve this problem.



Thanks.










share|cite|improve this question











$endgroup$












  • $begingroup$
    can you specify your definition of well.ordering.
    $endgroup$
    – J.F
    Jan 18 at 23:28










  • $begingroup$
    A set $A$ is well ordering if all no-empty subset of $A$ have a minimum element.
    $endgroup$
    – Lennis Mariana
    Jan 18 at 23:31










  • $begingroup$
    A very standard equivalent one (which is i guess the thing you have to prove) is the following : Every decreasing sequence of elements of $A$ must be finite.
    $endgroup$
    – J.F
    Jan 18 at 23:36












  • $begingroup$
    Ok, i think i have the idea, i'll try to prove in this way, thanks.
    $endgroup$
    – Lennis Mariana
    Jan 18 at 23:45










  • $begingroup$
    I can put this as an answer to close the question if you want.
    $endgroup$
    – J.F
    Jan 18 at 23:46














0












0








0





$begingroup$


"Show that the order $(A,<)$ is well ordering if and only if there no exists infinite descendant sequences in $A$".



Can you help me whit this problem, please, what happens is that my professor isn't gave us the definition of "infinite descendant sequences", so i haven't enough basis to solve this problem.



Thanks.










share|cite|improve this question











$endgroup$




"Show that the order $(A,<)$ is well ordering if and only if there no exists infinite descendant sequences in $A$".



Can you help me whit this problem, please, what happens is that my professor isn't gave us the definition of "infinite descendant sequences", so i haven't enough basis to solve this problem.



Thanks.







elementary-set-theory order-theory well-orders






share|cite|improve this question















share|cite|improve this question













share|cite|improve this question




share|cite|improve this question








edited Jan 18 at 23:32







Lennis Mariana

















asked Jan 18 at 23:14









Lennis MarianaLennis Mariana

255




255












  • $begingroup$
    can you specify your definition of well.ordering.
    $endgroup$
    – J.F
    Jan 18 at 23:28










  • $begingroup$
    A set $A$ is well ordering if all no-empty subset of $A$ have a minimum element.
    $endgroup$
    – Lennis Mariana
    Jan 18 at 23:31










  • $begingroup$
    A very standard equivalent one (which is i guess the thing you have to prove) is the following : Every decreasing sequence of elements of $A$ must be finite.
    $endgroup$
    – J.F
    Jan 18 at 23:36












  • $begingroup$
    Ok, i think i have the idea, i'll try to prove in this way, thanks.
    $endgroup$
    – Lennis Mariana
    Jan 18 at 23:45










  • $begingroup$
    I can put this as an answer to close the question if you want.
    $endgroup$
    – J.F
    Jan 18 at 23:46


















  • $begingroup$
    can you specify your definition of well.ordering.
    $endgroup$
    – J.F
    Jan 18 at 23:28










  • $begingroup$
    A set $A$ is well ordering if all no-empty subset of $A$ have a minimum element.
    $endgroup$
    – Lennis Mariana
    Jan 18 at 23:31










  • $begingroup$
    A very standard equivalent one (which is i guess the thing you have to prove) is the following : Every decreasing sequence of elements of $A$ must be finite.
    $endgroup$
    – J.F
    Jan 18 at 23:36












  • $begingroup$
    Ok, i think i have the idea, i'll try to prove in this way, thanks.
    $endgroup$
    – Lennis Mariana
    Jan 18 at 23:45










  • $begingroup$
    I can put this as an answer to close the question if you want.
    $endgroup$
    – J.F
    Jan 18 at 23:46
















$begingroup$
can you specify your definition of well.ordering.
$endgroup$
– J.F
Jan 18 at 23:28




$begingroup$
can you specify your definition of well.ordering.
$endgroup$
– J.F
Jan 18 at 23:28












$begingroup$
A set $A$ is well ordering if all no-empty subset of $A$ have a minimum element.
$endgroup$
– Lennis Mariana
Jan 18 at 23:31




$begingroup$
A set $A$ is well ordering if all no-empty subset of $A$ have a minimum element.
$endgroup$
– Lennis Mariana
Jan 18 at 23:31












$begingroup$
A very standard equivalent one (which is i guess the thing you have to prove) is the following : Every decreasing sequence of elements of $A$ must be finite.
$endgroup$
– J.F
Jan 18 at 23:36






$begingroup$
A very standard equivalent one (which is i guess the thing you have to prove) is the following : Every decreasing sequence of elements of $A$ must be finite.
$endgroup$
– J.F
Jan 18 at 23:36














$begingroup$
Ok, i think i have the idea, i'll try to prove in this way, thanks.
$endgroup$
– Lennis Mariana
Jan 18 at 23:45




$begingroup$
Ok, i think i have the idea, i'll try to prove in this way, thanks.
$endgroup$
– Lennis Mariana
Jan 18 at 23:45












$begingroup$
I can put this as an answer to close the question if you want.
$endgroup$
– J.F
Jan 18 at 23:46




$begingroup$
I can put this as an answer to close the question if you want.
$endgroup$
– J.F
Jan 18 at 23:46










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