Very basic question about pre-additive category












1












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I am trying to prove whether in a pre-additive category, $0_{Mor(y,z)}circ f=0_{Mor(x,z)}$ for objects $x,y,z$ and $fin Mor(x,y)$. Now, by bi-linearity of composition maps $$ 0_{Mor(y,z)}circ f+ 0_{Mor(y,z)}circ (-f)= 0_{Mor(y,z)} circ 0_{Mor(x,y)} $$



Putting $f=0_{Mor(x,y)}; ;$ we have $; ; 0_{Mor(y,z)} circ 0_{Mor(x,y)} =0_{Mor(x,z)}; ; $and we also get $; ; 0_{Mor(y,z)}circ f=-( 0_{Mor(y,z)}circ (-f))$. But I can't seem to progress any further.



Thanks in advance!










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  • 1




    $begingroup$
    Bilinearity of composition implies by definition $0circ f=0$ since the map $-circ f$ is a homomorphism of groups.
    $endgroup$
    – asdq
    Dec 31 '18 at 13:15
















1












$begingroup$


I am trying to prove whether in a pre-additive category, $0_{Mor(y,z)}circ f=0_{Mor(x,z)}$ for objects $x,y,z$ and $fin Mor(x,y)$. Now, by bi-linearity of composition maps $$ 0_{Mor(y,z)}circ f+ 0_{Mor(y,z)}circ (-f)= 0_{Mor(y,z)} circ 0_{Mor(x,y)} $$



Putting $f=0_{Mor(x,y)}; ;$ we have $; ; 0_{Mor(y,z)} circ 0_{Mor(x,y)} =0_{Mor(x,z)}; ; $and we also get $; ; 0_{Mor(y,z)}circ f=-( 0_{Mor(y,z)}circ (-f))$. But I can't seem to progress any further.



Thanks in advance!










share|cite|improve this question









$endgroup$








  • 1




    $begingroup$
    Bilinearity of composition implies by definition $0circ f=0$ since the map $-circ f$ is a homomorphism of groups.
    $endgroup$
    – asdq
    Dec 31 '18 at 13:15














1












1








1





$begingroup$


I am trying to prove whether in a pre-additive category, $0_{Mor(y,z)}circ f=0_{Mor(x,z)}$ for objects $x,y,z$ and $fin Mor(x,y)$. Now, by bi-linearity of composition maps $$ 0_{Mor(y,z)}circ f+ 0_{Mor(y,z)}circ (-f)= 0_{Mor(y,z)} circ 0_{Mor(x,y)} $$



Putting $f=0_{Mor(x,y)}; ;$ we have $; ; 0_{Mor(y,z)} circ 0_{Mor(x,y)} =0_{Mor(x,z)}; ; $and we also get $; ; 0_{Mor(y,z)}circ f=-( 0_{Mor(y,z)}circ (-f))$. But I can't seem to progress any further.



Thanks in advance!










share|cite|improve this question









$endgroup$




I am trying to prove whether in a pre-additive category, $0_{Mor(y,z)}circ f=0_{Mor(x,z)}$ for objects $x,y,z$ and $fin Mor(x,y)$. Now, by bi-linearity of composition maps $$ 0_{Mor(y,z)}circ f+ 0_{Mor(y,z)}circ (-f)= 0_{Mor(y,z)} circ 0_{Mor(x,y)} $$



Putting $f=0_{Mor(x,y)}; ;$ we have $; ; 0_{Mor(y,z)} circ 0_{Mor(x,y)} =0_{Mor(x,z)}; ; $and we also get $; ; 0_{Mor(y,z)}circ f=-( 0_{Mor(y,z)}circ (-f))$. But I can't seem to progress any further.



Thanks in advance!







category-theory homological-algebra






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asked Dec 31 '18 at 12:19









solgaleosolgaleo

9712




9712








  • 1




    $begingroup$
    Bilinearity of composition implies by definition $0circ f=0$ since the map $-circ f$ is a homomorphism of groups.
    $endgroup$
    – asdq
    Dec 31 '18 at 13:15














  • 1




    $begingroup$
    Bilinearity of composition implies by definition $0circ f=0$ since the map $-circ f$ is a homomorphism of groups.
    $endgroup$
    – asdq
    Dec 31 '18 at 13:15








1




1




$begingroup$
Bilinearity of composition implies by definition $0circ f=0$ since the map $-circ f$ is a homomorphism of groups.
$endgroup$
– asdq
Dec 31 '18 at 13:15




$begingroup$
Bilinearity of composition implies by definition $0circ f=0$ since the map $-circ f$ is a homomorphism of groups.
$endgroup$
– asdq
Dec 31 '18 at 13:15










1 Answer
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$begingroup$

The answer to your question is basically in asdq's comment, allow me to expand a little.



By bilinearity you have that for $f in Mor(x,y)$ the mapping
$$
begin{align*}
-circ f colon Mor(y,z) &to Mor(x,z) \
x mapsto x circ f
end{align*}
$$

is a group homomorphism, in particular it sends $0_{Mor(y,z)}$ into $0_{Mor(x,z)}$, that is that $0_{Mor(y,z)}circ f = 0_{Mor(x,z)}$.






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    $begingroup$

    The answer to your question is basically in asdq's comment, allow me to expand a little.



    By bilinearity you have that for $f in Mor(x,y)$ the mapping
    $$
    begin{align*}
    -circ f colon Mor(y,z) &to Mor(x,z) \
    x mapsto x circ f
    end{align*}
    $$

    is a group homomorphism, in particular it sends $0_{Mor(y,z)}$ into $0_{Mor(x,z)}$, that is that $0_{Mor(y,z)}circ f = 0_{Mor(x,z)}$.






    share|cite|improve this answer









    $endgroup$


















      1












      $begingroup$

      The answer to your question is basically in asdq's comment, allow me to expand a little.



      By bilinearity you have that for $f in Mor(x,y)$ the mapping
      $$
      begin{align*}
      -circ f colon Mor(y,z) &to Mor(x,z) \
      x mapsto x circ f
      end{align*}
      $$

      is a group homomorphism, in particular it sends $0_{Mor(y,z)}$ into $0_{Mor(x,z)}$, that is that $0_{Mor(y,z)}circ f = 0_{Mor(x,z)}$.






      share|cite|improve this answer









      $endgroup$
















        1












        1








        1





        $begingroup$

        The answer to your question is basically in asdq's comment, allow me to expand a little.



        By bilinearity you have that for $f in Mor(x,y)$ the mapping
        $$
        begin{align*}
        -circ f colon Mor(y,z) &to Mor(x,z) \
        x mapsto x circ f
        end{align*}
        $$

        is a group homomorphism, in particular it sends $0_{Mor(y,z)}$ into $0_{Mor(x,z)}$, that is that $0_{Mor(y,z)}circ f = 0_{Mor(x,z)}$.






        share|cite|improve this answer









        $endgroup$



        The answer to your question is basically in asdq's comment, allow me to expand a little.



        By bilinearity you have that for $f in Mor(x,y)$ the mapping
        $$
        begin{align*}
        -circ f colon Mor(y,z) &to Mor(x,z) \
        x mapsto x circ f
        end{align*}
        $$

        is a group homomorphism, in particular it sends $0_{Mor(y,z)}$ into $0_{Mor(x,z)}$, that is that $0_{Mor(y,z)}circ f = 0_{Mor(x,z)}$.







        share|cite|improve this answer












        share|cite|improve this answer



        share|cite|improve this answer










        answered Dec 31 '18 at 22:01









        Giorgio MossaGiorgio Mossa

        14.4k11750




        14.4k11750






























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