From: Jonathan Levin <jonathan.levin@sant.ox.ac.uk>
To: "bitcoin-development@lists.sourceforge.net"
	<bitcoin-development@lists.sourceforge.net>
Thread-Topic: Cut-through propagation of blocks
Thread-Index: AQHPd6vxYIXrqyO45kqgPDYZ/wCKiw==
Date: Sat, 24 May 2014 23:57:39 +0000
Message-ID: <86C2A90A-6619-45CD-94EC-009456471050@sant.ox.ac.uk>
References: <mailman.177181.1400974908.2207.bitcoin-development@lists.sourceforge.net>
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Subject: Re: [Bitcoin-development] Cut-through propagation of blocks
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I have done some work on incentives arising from block propagation times an=
d it turns out that Bitcoin is already quite good at establishing the prima=
cy of blocks by time despite what people think. Part of the reason for this=
 is the way that partitions on the network evolve as a block is propagated.=
 Typically at the moment, blocks reach over 50% of the network in 5 seconds=
. Reach being defined as a node receiving and validating a block. If we mak=
e an assumption that the hashing power of the network is uniformly distribu=
ted over the nodes (I know it is not a good assumption but can discuss it o=
ff the list). Then 50% of the hashing power are already building a block th=
at builds on top of the block that is already circulating. The probability =
that there is a collision on the network therefore falls fast and then the =
probability that the miner who propagated the first block wins given a coll=
ision occurs is rising. I think that block propagation times might actually=
 be a bigger issue for miners who are less well connected to the network in=
 the sense that they spend more time mining redundant problems and during t=
hat time may find blocks to compete with blocks that are already spreading =
throughout the network.

I have a paper that models this more formally and has some numerical simula=
tions but cannot publish it on the internet at present (University Regulati=
ons) but I am happy to share a version privately if anyone is interested.

Best,

Jonathan

--
Jonathan Levin
Co-Founder Coinometrics
http://www.coinometrics.com/
Postgraduate Economist | St Antony's College | Oxford University
@jony_levin
@Coinometrics





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I have done some work on incentives arising from block propagation times an=
d it turns out that Bitcoin is already quite good at establishing the prima=
cy of blocks by time despite what people think. Part of the reason for this=
 is the way that partitions on the
 network evolve as a block is propagated. Typically at the moment, blocks r=
each over 50% of the network in 5 seconds. Reach being defined as a node re=
ceiving and validating a block. If we make an assumption that the hashing p=
ower of the network is uniformly
 distributed over the nodes (I know it is not a good assumption but can dis=
cuss it off the list). Then 50% of the hashing power are already building a=
 block that builds on top of the block that is already circulating. The pro=
bability that there is a collision
 on the network therefore falls fast and then the probability that the mine=
r who propagated the first block wins given a collision occurs is rising. I=
 think that block propagation times might actually be a bigger issue for mi=
ners who are less well connected
 to the network in the sense that they spend more time mining redundant pro=
blems and during that time may find blocks to compete with blocks that are =
already spreading throughout the network.&nbsp;
<div><br>
</div>
<div>I have a paper that models this more formally and has some numerical s=
imulations but cannot publish it on the internet at present (University Reg=
ulations) but I am happy to share a version privately if anyone is interest=
ed.</div>
<div><br>
</div>
<div>Best,</div>
<div><br>
</div>
<div>Jonathan</div>
<div><br>
</div>
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--</div>
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<b>Jonathan Levin</b></div>
<div style=3D"font-weight: normal; color: rgb(0, 0, 0); font-family: Avenir=
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Co-Founder Coinometrics</div>
<div style=3D"font-weight: normal; color: rgb(0, 0, 0); font-family: Avenir=
; font-size: 11px; font-style: normal; font-variant: normal; letter-spacing=
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<a href=3D"http://www.coinometrics.com/">http://www.coinometrics.com/</a></=
div>
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t: 0px; text-transform: none; white-space: normal; widows: auto; word-spaci=
ng: 0px; -webkit-text-stroke-width: 0px;">
Postgraduate Economist | St Antony's College |&nbsp;Oxford University<br>
@jony_levin</div>
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; font-size: 11px; font-style: normal; font-variant: normal; letter-spacing=
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@Coinometrics<br>
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