Re: [RFC 0/9] bisect: allow git bisect to be used with repos containing damaged trees.

From: Jakub Narebski <jnareb@gmail.com>
Date: Jul 26, 2011, 07:43 UTC
Message-ID: <m3ei1dsd1x.fsf@localhost.localdomain>
In-Reply-To: <CAH3AnrrOdduUG_rS97fR_PRZAWb6y3uPa_oKDZenEX2gG-AvAQ@mail.gmail.com>

Jon Seymour <jon.seymour@gmail.com> writes:

Show 14 quoted lines

> On Tue, Jul 26, 2011 at 4:48 AM, Johannes Sixt <j6t@kdbg.org> wrote:
>> Am 25.07.2011 11:28, schrieb Jon Seymour:
>>> On Mon, Jul 25, 2011 at 4:35 AM, Junio C Hamano <gitster@pobox.com> wrote:
>>>> Jon Seymour <jon.seymour@gmail.com> writes:
>>
>> The fundamental preconditions of bisection are: that there is a single
>> event in the sequence, and that the effects of the event propagate to
>> the end of the sequence.
> 
> More correctly: the fundamental pre-condition of a single round of
> bisection finding an event of interest is as you say.
> 
> There is nothing that prevents multiple rounds of bisection being
> used, if required.

No, it is not true. Think of bisection as in original application, as numerical methods used to find root of one dimensional function. It works if there is single root between starting endpoints, or rather if endpoints have different signs.

Which means that it works in this case:

                        bad bad bad
                   BAD
   good good good

but won't work in this case:

   good good good               good good good
                   bad bad bad

-- 
Jakub Narębski