Non-void intersection of two sets











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Let $(t,x)$ be in $(0,infty)times(0,1$) with the constraint $x+t<1$. Let $(a,b)$ be a subset of $(0,1)$. I want to know for which values of $t$ we have $${(x,x+t)}cap{(a,b)}neqemptyset$$
or $${(x-t,x)}cap{(a,b)}neqemptyset$$ with the contraint $x-t<1$.



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    Let $(t,x)$ be in $(0,infty)times(0,1$) with the constraint $x+t<1$. Let $(a,b)$ be a subset of $(0,1)$. I want to know for which values of $t$ we have $${(x,x+t)}cap{(a,b)}neqemptyset$$
    or $${(x-t,x)}cap{(a,b)}neqemptyset$$ with the contraint $x-t<1$.



    Thank you.










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      up vote
      0
      down vote

      favorite









      up vote
      0
      down vote

      favorite











      Let $(t,x)$ be in $(0,infty)times(0,1$) with the constraint $x+t<1$. Let $(a,b)$ be a subset of $(0,1)$. I want to know for which values of $t$ we have $${(x,x+t)}cap{(a,b)}neqemptyset$$
      or $${(x-t,x)}cap{(a,b)}neqemptyset$$ with the contraint $x-t<1$.



      Thank you.










      share|cite|improve this question















      Let $(t,x)$ be in $(0,infty)times(0,1$) with the constraint $x+t<1$. Let $(a,b)$ be a subset of $(0,1)$. I want to know for which values of $t$ we have $${(x,x+t)}cap{(a,b)}neqemptyset$$
      or $${(x-t,x)}cap{(a,b)}neqemptyset$$ with the contraint $x-t<1$.



      Thank you.







      real-analysis analysis optimization






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      edited Nov 23 at 14:32

























      asked Nov 23 at 13:42









      Gustave

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      691211






















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          Its strange that you let $t in (0, infty)$ and $x in (0,1)$ but then restrict $t+x<1$. This means $t$ can't possibly be more than $1$. Also the restriction $x-t<1$ holds for all elements of this space since $t$ is positive and $x$ is less than $1$.



          That said, if $x>b$ then $(x,x+t) cap (a,b) = emptyset$. If $x in [a,b)$ then $(x,x+t) cap (a,b)$ is never empty. Finally if $x<a$ then $(x,x+t) cap (a,b)$ is non empty if and only if $x+t>a$.



          The $(x-t,x)$ case is similar.






          share|cite|improve this answer





















          • Thanks @Eric...
            – Gustave
            Nov 23 at 15:14











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          Its strange that you let $t in (0, infty)$ and $x in (0,1)$ but then restrict $t+x<1$. This means $t$ can't possibly be more than $1$. Also the restriction $x-t<1$ holds for all elements of this space since $t$ is positive and $x$ is less than $1$.



          That said, if $x>b$ then $(x,x+t) cap (a,b) = emptyset$. If $x in [a,b)$ then $(x,x+t) cap (a,b)$ is never empty. Finally if $x<a$ then $(x,x+t) cap (a,b)$ is non empty if and only if $x+t>a$.



          The $(x-t,x)$ case is similar.






          share|cite|improve this answer





















          • Thanks @Eric...
            – Gustave
            Nov 23 at 15:14















          up vote
          1
          down vote













          Its strange that you let $t in (0, infty)$ and $x in (0,1)$ but then restrict $t+x<1$. This means $t$ can't possibly be more than $1$. Also the restriction $x-t<1$ holds for all elements of this space since $t$ is positive and $x$ is less than $1$.



          That said, if $x>b$ then $(x,x+t) cap (a,b) = emptyset$. If $x in [a,b)$ then $(x,x+t) cap (a,b)$ is never empty. Finally if $x<a$ then $(x,x+t) cap (a,b)$ is non empty if and only if $x+t>a$.



          The $(x-t,x)$ case is similar.






          share|cite|improve this answer





















          • Thanks @Eric...
            – Gustave
            Nov 23 at 15:14













          up vote
          1
          down vote










          up vote
          1
          down vote









          Its strange that you let $t in (0, infty)$ and $x in (0,1)$ but then restrict $t+x<1$. This means $t$ can't possibly be more than $1$. Also the restriction $x-t<1$ holds for all elements of this space since $t$ is positive and $x$ is less than $1$.



          That said, if $x>b$ then $(x,x+t) cap (a,b) = emptyset$. If $x in [a,b)$ then $(x,x+t) cap (a,b)$ is never empty. Finally if $x<a$ then $(x,x+t) cap (a,b)$ is non empty if and only if $x+t>a$.



          The $(x-t,x)$ case is similar.






          share|cite|improve this answer












          Its strange that you let $t in (0, infty)$ and $x in (0,1)$ but then restrict $t+x<1$. This means $t$ can't possibly be more than $1$. Also the restriction $x-t<1$ holds for all elements of this space since $t$ is positive and $x$ is less than $1$.



          That said, if $x>b$ then $(x,x+t) cap (a,b) = emptyset$. If $x in [a,b)$ then $(x,x+t) cap (a,b)$ is never empty. Finally if $x<a$ then $(x,x+t) cap (a,b)$ is non empty if and only if $x+t>a$.



          The $(x-t,x)$ case is similar.







          share|cite|improve this answer












          share|cite|improve this answer



          share|cite|improve this answer










          answered Nov 23 at 14:44









          Eric

          2088




          2088












          • Thanks @Eric...
            – Gustave
            Nov 23 at 15:14


















          • Thanks @Eric...
            – Gustave
            Nov 23 at 15:14
















          Thanks @Eric...
          – Gustave
          Nov 23 at 15:14




          Thanks @Eric...
          – Gustave
          Nov 23 at 15:14


















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