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From: Sergio Demian Lerner <sergio.d.lerner@gmail.com>
Date: Thu, 24 Nov 2016 22:39:05 -0300
Message-ID: <CAKzdR-r7or+DF64qxT=HLUvrtdkSQD0hpO43kUjfWS-397+yHA@mail.gmail.com>
To: Peter R <peter_r@gmx.com>, 
	Bitcoin Protocol Discussion <bitcoin-dev@lists.linuxfoundation.org>
Content-Type: multipart/alternative; boundary=001a1137d72e632a910542163294
Subject: Re: [bitcoin-dev] The Excessive-Block Gate: How a Bitcoin Unlimited
 Node Deals With Large Blocks
Precedence: list

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Hi Peter,

How would a person or exchange decide to accept a payment in BU if it does
not know the gate policy of 51% of the miners?

Suppose that the exchange receives B1,S2,S3,S4 (a big block at height 1,
and 3 small blocks at height 2, 3 and 4), and an alternate chain A1,A2,A3
(three small blocks). The first is the longest, but the second may be the
one 51% of the miners will extend.

Without knowing  the policy of at least 51% of the miners (the maximum
acceptance depth) it's unclear if the exchange has to obey the longest
chain or the chain with higher probability of being extended.
If the maximum acceptance depth of the majority of miners is higher than 6
blocks, accepting a transaction with 6 confirmations is risky.
So BU would set a lower bound on the number of confirmations equal to the
maximum acceptance depth of the majority of miners.But miners do not
publish their acceptance depth, so basically users are clue-less. I think
miners should at least advertise their gate block size and acceptance depth
in their coinbase field.

Is there a game-theoretic analysis of confirmation blocks and their
probabilities in BU ?
Without a detailed analysis, unlimited block size seems a risky change to
Bitcoin, to me.

Regards, Sergio.


On Tue, Nov 22, 2016 at 1:31 PM, Peter R via bitcoin-dev <
bitcoin-dev@lists.linuxfoundation.org> wrote:

> Dear all,
>
> Bitcoin Unlimited=E2=80=99s market-based solution to the block-size limit=
 is
> slowly winning support from node operators and miners.  With this increas=
ed
> attention, many people are asking for a better explanation of how Bitcoin
> Unlimited actually works.  The article linked below describes how Bitcoin
> Unlimited=E2=80=99s excessive-block logic works from the perspective of a=
 single
> node. (I=E2=80=99m hoping to do a follow-up article that describe how thi=
s
> =E2=80=9Cnode-scale=E2=80=9D behavior facilitates the emergence of a flui=
d and organic
> block size limit at the network scale.)
>
> https://medium.com/@peter_r/the-excessive-block-gate-how-
> a-bitcoin-unlimited-node-deals-with-large-blocks-22a4a5c322d4
>
> Best regards,
> Peter R
>
> _______________________________________________
> bitcoin-dev mailing list
> bitcoin-dev@lists.linuxfoundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>
>

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<div dir=3D"ltr"><div><div><div>Hi Peter,<br><br>How would a person or exch=
ange decide to accept a payment in BU if it does not know the gate policy o=
f 51% of the miners?<br><br></div>Suppose that the exchange receives B1,S2,=
S3,S4 (a big block at height 1, and 3 small blocks at height 2, 3 and 4), a=
nd an alternate chain A1,A2,A3=C2=A0 (three small blocks). The first is the=
 longest, but the second may be the one 51% of the miners will extend.<br><=
br>Without knowing=C2=A0 the policy of at least 51% of the miners (the maxi=
mum acceptance depth) it&#39;s unclear if the exchange has to obey the long=
est chain or the chain with higher probability of being extended. <br>If th=
e maximum acceptance depth of the majority of miners is higher than 6 block=
s, accepting a transaction with 6 confirmations is risky.<br></div>So BU wo=
uld set a lower bound on the number of confirmations equal to the maximum a=
cceptance depth of the majority of miners.But miners do not publish their a=
cceptance depth, so basically users are clue-less. I think miners should at=
 least advertise their gate block size and acceptance depth in their coinba=
se field.<br></div><div><br></div><div>Is there a game-theoretic analysis o=
f confirmation blocks and their probabilities in BU ?<br></div><div>Without=
 a detailed analysis, unlimited block size seems a risky change to Bitcoin,=
 to me.<br><br>Regards, Sergio.<br></div><div><br></div><div><div><div><br>=
</div></div></div></div><div class=3D"gmail_extra"><br><div class=3D"gmail_=
quote">On Tue, Nov 22, 2016 at 1:31 PM, Peter R via bitcoin-dev <span dir=
=3D"ltr">&lt;<a href=3D"mailto:bitcoin-dev@lists.linuxfoundation.org" targe=
t=3D"_blank">bitcoin-dev@lists.linuxfoundation.org</a>&gt;</span> wrote:<br=
><blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1=
px #ccc solid;padding-left:1ex"><div style=3D"word-wrap:break-word"><div>De=
ar all,</div><div><br></div><div>Bitcoin Unlimited=E2=80=99s market-based s=
olution to the block-size limit is slowly winning support from node operato=
rs and miners.=C2=A0 With this increased attention, many people are asking =
for a better explanation of how Bitcoin Unlimited actually works.=C2=A0 The=
 article linked below describes how Bitcoin Unlimited=E2=80=99s excessive-b=
lock logic works from the perspective of a single node. (I=E2=80=99m hoping=
 to do a follow-up article that describe how this =E2=80=9Cnode-scale=E2=80=
=9D behavior facilitates the emergence of a fluid and organic block size li=
mit at the network scale.)</div><div><br></div><a href=3D"https://medium.co=
m/@peter_r/the-excessive-block-gate-how-a-bitcoin-unlimited-node-deals-with=
-large-blocks-22a4a5c322d4" target=3D"_blank">https://medium.com/@peter_r/<=
wbr>the-excessive-block-gate-how-<wbr>a-bitcoin-unlimited-node-<wbr>deals-w=
ith-large-blocks-<wbr>22a4a5c322d4</a><div><br></div><div>Best regards,</di=
v><div>Peter R</div></div><br>______________________________<wbr>__________=
_______<br>
bitcoin-dev mailing list<br>
<a href=3D"mailto:bitcoin-dev@lists.linuxfoundation.org">bitcoin-dev@lists.=
<wbr>linuxfoundation.org</a><br>
<a href=3D"https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev" =
rel=3D"noreferrer" target=3D"_blank">https://lists.linuxfoundation.<wbr>org=
/mailman/listinfo/bitcoin-<wbr>dev</a><br>
<br></blockquote></div><br></div>

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