From: "H. Peter Anvin" <hpa@zytor.com>
To: Ben Clifford <benc@hawaga.org.uk>
Cc: Johannes Schindelin <Johannes.Schindelin@gmx.de>,
Git Mailing List <git@vger.kernel.org>
Subject: Re: Problem merging
Date: Sun, 27 Nov 2005 13:24:44 -0800 [thread overview]
Message-ID: <438A241C.5010007@zytor.com> (raw)
In-Reply-To: <D8B7EF65-9D0C-4706-B248-4B7C118C16BF@hawaga.org.uk>
Ben Clifford wrote:
> On 24 Nov 2005, at 00:49, Johannes Schindelin wrote:
>
>>
>> I think nobody is. Since there are infinitely many files having the same
>> SHA1 (pigeon-hole principle),
>
> hmm... pigeon-hole principle is just that there exists two files that
> have the same SHA-1 as each other... doesn't say anything about *all*
> SHA-1s, though?
>
There are an infinite number of possible files (specifically,
aleph-null.) There are a finite number of possible SHA-1's
(specifically, 1461501637330902918203684832716283019655932542976.)
Therefore the pidgeon-hole principle tells you there must be at least
one SHA-1 value that hashes an infinite number of files (aleph-null, again.)
Given that SHA-1 is believed to be uniformly distributed, it's quite
likely *ALL* SHA-1's hash an infinite number of files, but the
pigeon-hole principle can't tell you that.
-hpa
next prev parent reply other threads:[~2005-11-27 21:25 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-11-23 2:50 Problem merging Luben Tuikov
2005-11-23 3:06 ` Junio C Hamano
2005-11-23 3:41 ` Luben Tuikov
2005-11-23 14:49 ` Johannes Schindelin
2005-11-24 10:54 ` Ben Clifford
2005-11-25 1:13 ` Johannes Schindelin
2005-11-25 1:35 ` Andreas Ericsson
2005-11-27 21:24 ` H. Peter Anvin [this message]
2005-11-23 8:59 ` Fredrik Kuivinen
2005-11-23 19:48 ` Junio C Hamano
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