Sorry, I was quoting the only parts of the sentence.
What I meant was that I would change
Conversely, if I∉U, this implies that N/I∈U, which means that a, b disagree at almost all positions, so they probably shouldn’t be equal.
to
Conversely, if I∉U, this implies that N∖I∈U, which means that a, b disagree at almost all positions, so they probably shouldn’t be equal.
Sorry, I was quoting the only parts of the sentence.
What I meant was that I would change
to