$a_{n+m+2} leq a_m+a_n+g(n)$ with $g(n) = o(n)$. Show that $a_n geq (n+2)lambda-g(n)$ where $lambda = lim...











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I was working on the proof of the exponential decay on supercritical percolation as shown in Grimmett's Percolation (1999, 2 ed. pg 206 - 210) and he uses as a lemma a form of the subadditive theorem (fekete) in which he states (he says it is easy to find) that




if you have a sequence $(a_n)_n$ such that $a_{n+m+2} leq a_m+a_n+g(n)$ and $lim_{n to infty} frac{g(n)}{n}=0$ then




  • the limit $lim_{n to infty} frac{a_n}{n} = lambda$ exists and it's equal to the $inf left{frac{a_n}{n}right}$.


  • $a_n geq (n+2)lambda-g(n);forall n$.





Now, although I coundn't prove the existence of the limit using only what was stated on the theorem, I manage to prove it adding some restrictions which are valid on Grimmet's theorem (I asked it in here: Subadditive lemma for $a_{m+n+2}leq a_n+a_m+g(m)$ and I found that, in my application, the last condition was satisfied).



Now assuming the limit exists, I couldn't manage to show that $$a_ngeq (n+2) lambda-g(n)$$



Any tips on how to proceed? Thanks in advance.










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    I was working on the proof of the exponential decay on supercritical percolation as shown in Grimmett's Percolation (1999, 2 ed. pg 206 - 210) and he uses as a lemma a form of the subadditive theorem (fekete) in which he states (he says it is easy to find) that




    if you have a sequence $(a_n)_n$ such that $a_{n+m+2} leq a_m+a_n+g(n)$ and $lim_{n to infty} frac{g(n)}{n}=0$ then




    • the limit $lim_{n to infty} frac{a_n}{n} = lambda$ exists and it's equal to the $inf left{frac{a_n}{n}right}$.


    • $a_n geq (n+2)lambda-g(n);forall n$.





    Now, although I coundn't prove the existence of the limit using only what was stated on the theorem, I manage to prove it adding some restrictions which are valid on Grimmet's theorem (I asked it in here: Subadditive lemma for $a_{m+n+2}leq a_n+a_m+g(m)$ and I found that, in my application, the last condition was satisfied).



    Now assuming the limit exists, I couldn't manage to show that $$a_ngeq (n+2) lambda-g(n)$$



    Any tips on how to proceed? Thanks in advance.










    share|cite|improve this question
























      up vote
      1
      down vote

      favorite









      up vote
      1
      down vote

      favorite











      I was working on the proof of the exponential decay on supercritical percolation as shown in Grimmett's Percolation (1999, 2 ed. pg 206 - 210) and he uses as a lemma a form of the subadditive theorem (fekete) in which he states (he says it is easy to find) that




      if you have a sequence $(a_n)_n$ such that $a_{n+m+2} leq a_m+a_n+g(n)$ and $lim_{n to infty} frac{g(n)}{n}=0$ then




      • the limit $lim_{n to infty} frac{a_n}{n} = lambda$ exists and it's equal to the $inf left{frac{a_n}{n}right}$.


      • $a_n geq (n+2)lambda-g(n);forall n$.





      Now, although I coundn't prove the existence of the limit using only what was stated on the theorem, I manage to prove it adding some restrictions which are valid on Grimmet's theorem (I asked it in here: Subadditive lemma for $a_{m+n+2}leq a_n+a_m+g(m)$ and I found that, in my application, the last condition was satisfied).



      Now assuming the limit exists, I couldn't manage to show that $$a_ngeq (n+2) lambda-g(n)$$



      Any tips on how to proceed? Thanks in advance.










      share|cite|improve this question













      I was working on the proof of the exponential decay on supercritical percolation as shown in Grimmett's Percolation (1999, 2 ed. pg 206 - 210) and he uses as a lemma a form of the subadditive theorem (fekete) in which he states (he says it is easy to find) that




      if you have a sequence $(a_n)_n$ such that $a_{n+m+2} leq a_m+a_n+g(n)$ and $lim_{n to infty} frac{g(n)}{n}=0$ then




      • the limit $lim_{n to infty} frac{a_n}{n} = lambda$ exists and it's equal to the $inf left{frac{a_n}{n}right}$.


      • $a_n geq (n+2)lambda-g(n);forall n$.





      Now, although I coundn't prove the existence of the limit using only what was stated on the theorem, I manage to prove it adding some restrictions which are valid on Grimmet's theorem (I asked it in here: Subadditive lemma for $a_{m+n+2}leq a_n+a_m+g(m)$ and I found that, in my application, the last condition was satisfied).



      Now assuming the limit exists, I couldn't manage to show that $$a_ngeq (n+2) lambda-g(n)$$



      Any tips on how to proceed? Thanks in advance.







      real-analysis analysis convergence percolation






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      asked Nov 21 at 21:20









      Matheus barros castro

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