The IOTA Whitepaper refers to N but never defines what N means. Can anyone tell me what the N means in Section 3 and explain in words what the equation means? Thanks!

Observe that at any fixed time t the set of transactions that were tips at some At least in the case where the nodes moment s ∈ [ t,t + h(Lo,N)] typically constitutes a cutset. Any path from a transaction issued at time t′ > t to the genesis must pass through this set

  • Also, you may want to register on iotatangle.slack.com and join #tanglemath, to get questions like this one answered in a more informal context.
    – Phil-ZXX
    Jan 15, 2018 at 0:13
  • I am not sure how to join Iota slack. It seems like I need the admin to give me an invite.
    – Bill Bisco
    Jan 15, 2018 at 19:11

1 Answer 1


Parameter N was defined in an earlier version of the whitepaper as "total number of transactions". However, the dependency of h on L and N (as seen in your quote) has since been removed, and all the references to N should have been updated.

Bottom line, it seems like a typo and you can think of h(L,N) as just h.

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