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From: Paul Lyon <pmlyon@hotmail.ca>
To: Mike Hearn <mike@plan99.net>, Richard Moore <me@ricmoo.com>
Date: Tue, 15 Jul 2014 10:56:20 -0300
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Cc: Bitcoin Dev <bitcoin-development@lists.sourceforge.net>
Subject: Re: [Bitcoin-development] Self-dependency transaction question...
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Thankfully those two duplicated transactions were never spent when they fir=
st appeared. Because of that=2C I chose to not not add them to the UTXO at =
all when they first appear. When the duplicates appear they get added to th=
e UTXO successfully because the earlier=2C conflicting versions are not pre=
sent. That way you can carry on assuming that all transaction hashes are un=
ique=2C and enforce that rule over the entire blockchain.

Date: Mon=2C 14 Jul 2014 13:18:22 +0200
From: mike@plan99.net
To: me@ricmoo.com
CC: bitcoin-development@lists.sourceforge.net
Subject: Re: [Bitcoin-development] Self-dependency transaction question...

Conceptually all transactions in the block chain lie on a single timeline. =
The fact that we quantise that timeline into blocks is in many ways neither=
 here nor there - it's still a strict line. =0A=

What can happen and you must be aware of is duplicated transactions. Satosh=
i sort of assumed this could never happen because everything is hash based=
=2C but forgot that duplicating coinbases is possible and at one point this=
 did happen. It was banned by a rule change afterwards but you still must b=
e able to process the older parts of the chain that have this. There is a B=
IP that covers the new rule.=0A=

=0A=

---------------------------------------------------------------------------=
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Want fast and easy access to all the code in your enterprise? Index and=0A=
search up to 200=2C000 lines of code with a free copy of Black Duck=AE=0A=
Code Sight=99 - the same software that powers the world's largest code=0A=
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<body class=3D'hmmessage'><div dir=3D'ltr'>Thankfully those two duplicated =
transactions were never spent when they first appeared. Because of that=2C =
I chose to not not add them to the UTXO at all when they first appear. When=
 the duplicates appear they get added to the UTXO successfully because the =
earlier=2C conflicting versions are not present.&nbsp=3BThat way you can ca=
rry on assuming that all transaction hashes are unique=2C and enforce that =
rule over the entire blockchain.<br><br><div><hr id=3D"stopSpelling">Date: =
Mon=2C 14 Jul 2014 13:18:22 +0200<br>From: mike@plan99.net<br>To: me@ricmoo=
.com<br>CC: bitcoin-development@lists.sourceforge.net<br>Subject: Re: [Bitc=
oin-development] Self-dependency transaction question...<br><br><div dir=3D=
"ltr"><div class=3D"ecxgmail_extra"><div class=3D"ecxgmail_quote"><div>Conc=
eptually all transactions in the block chain lie on a single timeline. The =
fact that we quantise that timeline into blocks is in many ways neither her=
e nor there - it's still a strict line.&nbsp=3B</div>=0A=
<div><br></div><div>What <i>can</i>&nbsp=3Bhappen and you must be aware of =
is duplicated transactions. Satoshi sort of assumed this could never happen=
 because everything is hash based=2C but forgot that duplicating coinbases =
is possible and at one point this did happen. It was banned by a rule chang=
e afterwards but you still must be able to process the older parts of the c=
hain that have this. There is a BIP that covers the new rule.</div>=0A=
<div><br></div></div></div></div>=0A=
<br>-----------------------------------------------------------------------=
-------=0A=
Want fast and easy access to all the code in your enterprise? Index and=0A=
search up to 200=2C000 lines of code with a free copy of Black Duck=AE=0A=
Code Sight=99 - the same software that powers the world's largest code=0A=
search on Ohloh=2C the Black Duck Open Hub! Try it now.=0A=
http://p.sf.net/sfu/bds<br>_______________________________________________=
=0A=
Bitcoin-development mailing list=0A=
Bitcoin-development@lists.sourceforge.net=0A=
https://lists.sourceforge.net/lists/listinfo/bitcoin-development</div> 		 	=
   		  </div></body>
</html>=

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