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Discussion on: RUM Conjecture - Reasoning About Data Access

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Replies for: Hello, Nice post. So you say you are using this formula on your post: UO = (BU + AU) / BU + RO But i do not see it in action. With said formula ...

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frosnerd profile image
Frank Rosner •

Ok I read the post again and I'm not sure if we have UO = 2 somewhere.

  • In the read optimal case, we do not have any RO associated with an update as we know the position by index without reading the data.
  • In the update optimal case, we also do not have any RO as we simply append to the log.
  • In the memory optimal case we can have UO > N, as we need to perform N reads in case the element to be inserted is not part of the set.

Does it make sense?

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Nick Polyderopoulos •

Hmmm,
For the first case, for us to know the position by index shouldn't need to read the position first ?

For the third case i did not understand what are you saying.

Thanks,

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frosnerd profile image
Frank Rosner •

For the first case, for us to know the position by index shouldn't need to read the position first ?

What do you mean by reading the position? We can simple insert or delete the value without knowing whether it was there already.

For the third case i did not understand what are you saying.

What is it that you don't understand?