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From: Jim Posen <jim.posen@gmail.com>
To: pieter.wuille@gmail.com,
	 Bitcoin Protocol Discussion
	<bitcoin-dev@lists.linuxfoundation.org>
Subject: Re: [bitcoin-dev] Minimizing the redundancy in Golomb Coded Sets
Date: Tue, 29 May 2018 15:38:01 -0700	[thread overview]
Message-ID: <CADZtCShF-sGNfjSaOdmK=YMOdvimN2b_a1vXmJv_XHKxvn14Zw@mail.gmail.com> (raw)
In-Reply-To: <CAAS2fgQSS7R+PtmpcXJqjeXWnLa8S8O_1nFgdCYiLqRYbQM3QQ@mail.gmail.com>


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This is a really cool finding, thanks Pieter!

I did some more analysis on selecting a good P value to reduce total data
downloaded considering both filters themselves and blocks in the case of
false positive matches, using data from mainnet. The quantity it minimizes
is:

filter_size(N, B) + block_size * false_positive_probability(C, N, B)

N is the number of filter elements per block
B is the Golomb-Rice coding parameter
C is the number of filter elements watched by the client

The main result is that:

For C = 10, B = 13 is optimal
For C = 100, B = 16 is optimal
For C = 1,000, B = 20 is optimal
For C = 10,000, B = 23 is optimal

So any value of B in the range 16 to 20 seems reasonable, with M = 1.4971 *
2^B for optimal compression, as Pieter derived. The selection of the
parameter depends on the target number of elements that a client may watch.

I attached some of the results, and would be happy to share the CSV and raw
notebook if people are interested.


On Fri, May 25, 2018 at 2:14 PM Gregory Maxwell via bitcoin-dev <
bitcoin-dev@lists.linuxfoundation.org> wrote:

> On Fri, May 25, 2018 at 6:42 PM, Gregory Maxwell <greg@xiph.org> wrote:
> > configuration is roughly right, then M=1569861 and rice parameter 19
> > should be used.
>
> That should have been M=784931 B=19  ... paste error.
> _______________________________________________
> bitcoin-dev mailing list
> bitcoin-dev@lists.linuxfoundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>

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  reply	other threads:[~2018-05-29 22:38 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-25 17:54 [bitcoin-dev] Minimizing the redundancy in Golomb Coded Sets Pieter Wuille
2018-05-25 18:42 ` Gregory Maxwell
2018-05-25 21:13   ` Gregory Maxwell
2018-05-29 22:38     ` Jim Posen [this message]
2018-05-30  3:10       ` Lucas Ontivero

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