3 ms·

Most repositories contain more than 2 commits.

• anamexis 4y ago
  Fine, 3 in a trillion.
  • CodesInChaos 4y ago
    You're right that the chance that two specific 10 digit hashes collide is 1 in a trillion. But the chance of a collision between a specific commit and any other commit goes up linearly, so for the Linux repository it's about 1 million / 1 trillion so 1 in a million. The chance of a collision between a any two commits goes up quadratically (while it's small), and becomes ~50% when you reach the square-root of 1 trillion, i.e. 1 million. So there is a good chance the Linux repository already contains colliding 10 digit hashes, and if they don't exist yet, it'll likely happen during the next couple of years.
    • faho 4y ago
      What you are alluding to is the "Birthday problem". https://en.wikipedia.org/wiki/Birthday_problem https://en.wikipedia.org/wiki/Birthday_problem
    • anamexis 4y ago
      Yes, there is a good chance there is already a 10 digit hash collision in the Linux repository. But if you pick an arbitrary commit to cite in a research paper, it's still 1 in a million that that particular commit has a collision. And this is for a repo which has to be in the 99.999th percentile of number of commits.