Orthogonal bipolar vectors in 3-dimensions [closed]












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Suppose the vectors must consist of only 1 and - 1 (bipolar). This binary encoding is common for many neural networks.



Then can two 3D bipolar vectors be orthogonal? Orthogonal vectors can be successfully stored and retrieved in an auto-association memory network (like Hopfield).



As I try to figure out a dot product of any two of such vectors to be zero, I can't find one.










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closed as off-topic by Morgan Rodgers, RRL, Lord Shark the Unknown, mrtaurho, max_zorn Jan 14 at 7:16


This question appears to be off-topic. The users who voted to close gave this specific reason:


  • "This question is missing context or other details: Please provide additional context, which ideally explains why the question is relevant to you and our community. Some forms of context include: background and motivation, relevant definitions, source, possible strategies, your current progress, why the question is interesting or important, etc." – Morgan Rodgers, RRL, Lord Shark the Unknown, mrtaurho, max_zorn

If this question can be reworded to fit the rules in the help center, please edit the question.












  • 2




    $begingroup$
    I don't quite get why this question was closed. However, the answer is simple: two such vectors $v,win{-1,1}^{2n}$ (in even dimensions) are orthogonal if and only if they differ in exactly $n$ components. In odd dimensions, no two such vectors can be orthogonal.
    $endgroup$
    – M. Winter
    Jan 19 at 12:39


















0












$begingroup$


Suppose the vectors must consist of only 1 and - 1 (bipolar). This binary encoding is common for many neural networks.



Then can two 3D bipolar vectors be orthogonal? Orthogonal vectors can be successfully stored and retrieved in an auto-association memory network (like Hopfield).



As I try to figure out a dot product of any two of such vectors to be zero, I can't find one.










share|cite|improve this question











$endgroup$



closed as off-topic by Morgan Rodgers, RRL, Lord Shark the Unknown, mrtaurho, max_zorn Jan 14 at 7:16


This question appears to be off-topic. The users who voted to close gave this specific reason:


  • "This question is missing context or other details: Please provide additional context, which ideally explains why the question is relevant to you and our community. Some forms of context include: background and motivation, relevant definitions, source, possible strategies, your current progress, why the question is interesting or important, etc." – Morgan Rodgers, RRL, Lord Shark the Unknown, mrtaurho, max_zorn

If this question can be reworded to fit the rules in the help center, please edit the question.












  • 2




    $begingroup$
    I don't quite get why this question was closed. However, the answer is simple: two such vectors $v,win{-1,1}^{2n}$ (in even dimensions) are orthogonal if and only if they differ in exactly $n$ components. In odd dimensions, no two such vectors can be orthogonal.
    $endgroup$
    – M. Winter
    Jan 19 at 12:39
















0












0








0





$begingroup$


Suppose the vectors must consist of only 1 and - 1 (bipolar). This binary encoding is common for many neural networks.



Then can two 3D bipolar vectors be orthogonal? Orthogonal vectors can be successfully stored and retrieved in an auto-association memory network (like Hopfield).



As I try to figure out a dot product of any two of such vectors to be zero, I can't find one.










share|cite|improve this question











$endgroup$




Suppose the vectors must consist of only 1 and - 1 (bipolar). This binary encoding is common for many neural networks.



Then can two 3D bipolar vectors be orthogonal? Orthogonal vectors can be successfully stored and retrieved in an auto-association memory network (like Hopfield).



As I try to figure out a dot product of any two of such vectors to be zero, I can't find one.







linear-algebra






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share|cite|improve this question













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share|cite|improve this question








edited Jan 19 at 12:45







Ahmad

















asked Jan 13 at 15:58









AhmadAhmad

22418




22418




closed as off-topic by Morgan Rodgers, RRL, Lord Shark the Unknown, mrtaurho, max_zorn Jan 14 at 7:16


This question appears to be off-topic. The users who voted to close gave this specific reason:


  • "This question is missing context or other details: Please provide additional context, which ideally explains why the question is relevant to you and our community. Some forms of context include: background and motivation, relevant definitions, source, possible strategies, your current progress, why the question is interesting or important, etc." – Morgan Rodgers, RRL, Lord Shark the Unknown, mrtaurho, max_zorn

If this question can be reworded to fit the rules in the help center, please edit the question.







closed as off-topic by Morgan Rodgers, RRL, Lord Shark the Unknown, mrtaurho, max_zorn Jan 14 at 7:16


This question appears to be off-topic. The users who voted to close gave this specific reason:


  • "This question is missing context or other details: Please provide additional context, which ideally explains why the question is relevant to you and our community. Some forms of context include: background and motivation, relevant definitions, source, possible strategies, your current progress, why the question is interesting or important, etc." – Morgan Rodgers, RRL, Lord Shark the Unknown, mrtaurho, max_zorn

If this question can be reworded to fit the rules in the help center, please edit the question.








  • 2




    $begingroup$
    I don't quite get why this question was closed. However, the answer is simple: two such vectors $v,win{-1,1}^{2n}$ (in even dimensions) are orthogonal if and only if they differ in exactly $n$ components. In odd dimensions, no two such vectors can be orthogonal.
    $endgroup$
    – M. Winter
    Jan 19 at 12:39
















  • 2




    $begingroup$
    I don't quite get why this question was closed. However, the answer is simple: two such vectors $v,win{-1,1}^{2n}$ (in even dimensions) are orthogonal if and only if they differ in exactly $n$ components. In odd dimensions, no two such vectors can be orthogonal.
    $endgroup$
    – M. Winter
    Jan 19 at 12:39










2




2




$begingroup$
I don't quite get why this question was closed. However, the answer is simple: two such vectors $v,win{-1,1}^{2n}$ (in even dimensions) are orthogonal if and only if they differ in exactly $n$ components. In odd dimensions, no two such vectors can be orthogonal.
$endgroup$
– M. Winter
Jan 19 at 12:39






$begingroup$
I don't quite get why this question was closed. However, the answer is simple: two such vectors $v,win{-1,1}^{2n}$ (in even dimensions) are orthogonal if and only if they differ in exactly $n$ components. In odd dimensions, no two such vectors can be orthogonal.
$endgroup$
– M. Winter
Jan 19 at 12:39












1 Answer
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There are only eight vectors in three dimensions whose entries are $pm1$. The summands of the dot product between any two of these vectors are also $pm1$, so if the dot product were to be zero there would have to be equal numbers of $+1$ and $-1$ summands, hence an even-length vector. But 3 is an odd number, so no two 3-dimensional "bipolar" vectors are orthogonal.



The same result applies to other odd-dimensional Euclidean vector spaces.






share|cite|improve this answer









$endgroup$




















    1 Answer
    1






    active

    oldest

    votes








    1 Answer
    1






    active

    oldest

    votes









    active

    oldest

    votes






    active

    oldest

    votes









    1












    $begingroup$

    There are only eight vectors in three dimensions whose entries are $pm1$. The summands of the dot product between any two of these vectors are also $pm1$, so if the dot product were to be zero there would have to be equal numbers of $+1$ and $-1$ summands, hence an even-length vector. But 3 is an odd number, so no two 3-dimensional "bipolar" vectors are orthogonal.



    The same result applies to other odd-dimensional Euclidean vector spaces.






    share|cite|improve this answer









    $endgroup$


















      1












      $begingroup$

      There are only eight vectors in three dimensions whose entries are $pm1$. The summands of the dot product between any two of these vectors are also $pm1$, so if the dot product were to be zero there would have to be equal numbers of $+1$ and $-1$ summands, hence an even-length vector. But 3 is an odd number, so no two 3-dimensional "bipolar" vectors are orthogonal.



      The same result applies to other odd-dimensional Euclidean vector spaces.






      share|cite|improve this answer









      $endgroup$
















        1












        1








        1





        $begingroup$

        There are only eight vectors in three dimensions whose entries are $pm1$. The summands of the dot product between any two of these vectors are also $pm1$, so if the dot product were to be zero there would have to be equal numbers of $+1$ and $-1$ summands, hence an even-length vector. But 3 is an odd number, so no two 3-dimensional "bipolar" vectors are orthogonal.



        The same result applies to other odd-dimensional Euclidean vector spaces.






        share|cite|improve this answer









        $endgroup$



        There are only eight vectors in three dimensions whose entries are $pm1$. The summands of the dot product between any two of these vectors are also $pm1$, so if the dot product were to be zero there would have to be equal numbers of $+1$ and $-1$ summands, hence an even-length vector. But 3 is an odd number, so no two 3-dimensional "bipolar" vectors are orthogonal.



        The same result applies to other odd-dimensional Euclidean vector spaces.







        share|cite|improve this answer












        share|cite|improve this answer



        share|cite|improve this answer










        answered Jan 13 at 16:01









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        41.8k1372101















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