IBM Research | Ponder This | April 2009 solutions
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April 2009

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f(x) = ((((x * c1) & c2) * c3) & c4) % c5, where
c1 = (2792-1)/(233-1);
c2 = (2816-1)/(234-1);
c3 = 1+234+23*34+24*34+28*34;
c4 = (21088-1)/(234-1)
c5 = 233-1;

We encoded a linear erasure code using O(1) operations, thanks to Eli Biham who gave us a simpler solution. A nice discussion on this issue can be found at (link resides outside of and the links from it.

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