From: "Russell O'Connor" <roconnor@blockstream•io>
To: Peter Todd <pete@petertodd•org>,
Bitcoin Protocol Discussion
<bitcoin-dev@lists•linuxfoundation.org>
Subject: Re: [bitcoin-dev] A Method for Computing Merkle Roots of Annotated Binary Trees
Date: Sat, 27 May 2017 18:07:07 -0400 [thread overview]
Message-ID: <CAMZUoKmAsxZFaLoOeAQT-YwCJBZ4z+qWJtRHPOXKTyqG7EAsfw@mail.gmail.com> (raw)
In-Reply-To: <CAMZUoKkS8azx7Gooo3D+H_gdGdTNiNtwwNVbvU0u7HzOfdUSBg@mail.gmail.com>
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On May 28, 2017 06:09, "Russell O'Connor" <roconnor@blockstream•io> wrote:
On May 28, 2017 03:16, "Peter Todd" <pete@petertodd•org> wrote:
On Mon, May 22, 2017 at 06:32:38PM -0400, Russell O'Connor wrote:
> On May 22, 2017 23:05, "Peter Todd" <pete@petertodd•org> wrote:
>
> On Mon, May 22, 2017 at 03:05:49AM -0400, Russell O'Connor via bitcoin-dev
> wrote:
> > MerkleRoot := SHA256(SHA256(LeftRoot ⋅ RightRoot))
> > sha256Compress : Word256 × Word512 -> Word256
>
> To be clear, what math operations do you mean by "⋅" and "×"?
>
>
> By "⋅", I usually mean concatenation (though I also use it for function
> composition in one instance). By "×", I mean the Cartesian product.
Cartesian product can mean a lot of things.
What specifically do you mean by "cartesian product" here?
Oops, I forgot to reply all. Below is my reply.
Given two types A and B, then A × B is the type of pairs of A and B in the
sense of type theory as used in Standard ML or Haskell or other typed
languages.
To follow up, by "sha256Compress : Word256 × Word512 -> Word256" I mean
that sha256Compress is a function that takes two arguments, the first being
a 256 bit word and the second being a 512 bit word, and returns a 256 bit
word (or equivalently sha256Compress is a function that takes a pair as
input, the first component being a 256 bit word and the second component
being a 512 bit word, and returns a 256 bit word).
sha256Compress is meant to be the compression function defined by the
SHA256 standard, though nothing here depends on anything more that its type
signature.
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next prev parent reply other threads:[~2017-05-27 22:07 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-22 7:05 Russell O'Connor
2017-05-22 14:05 ` Peter Todd
2017-05-22 22:32 ` Russell O'Connor
2017-05-27 17:41 ` Peter Todd
[not found] ` <CAMZUoKkS8azx7Gooo3D+H_gdGdTNiNtwwNVbvU0u7HzOfdUSBg@mail.gmail.com>
2017-05-27 22:07 ` Russell O'Connor [this message]
2017-05-23 6:06 ` Bram Cohen
2017-05-28 8:26 ` Peter Todd
2017-05-29 14:55 ` Russell O'Connor
2017-05-29 16:10 ` Peter Todd
2017-06-01 15:10 ` Russell O'Connor
2017-06-27 4:13 ` Peter Todd
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