<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=us-ascii">
<meta name="Generator" content="Microsoft Word 15 (filtered medium)">
<style><!--
/* Font Definitions */
@font-face
{font-family:"Cambria Math";
panose-1:2 4 5 3 5 4 6 3 2 4;}
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0in;
margin-bottom:.0001pt;
font-size:11.0pt;
font-family:"Calibri",sans-serif;}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:#0563C1;
text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
{mso-style-priority:99;
color:#954F72;
text-decoration:underline;}
span.EmailStyle17
{mso-style-type:personal-compose;
font-family:"Calibri",sans-serif;
color:windowtext;}
.MsoChpDefault
{mso-style-type:export-only;
font-family:"Calibri",sans-serif;}
@page WordSection1
{size:8.5in 11.0in;
margin:56.7pt 42.5pt 56.7pt 85.05pt;}
div.WordSection1
{page:WordSection1;}
--></style><!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</o:shapelayout></xml><![endif]-->
</head>
<body lang="EN-US" link="#0563C1" vlink="#954F72">
<div class="WordSection1">
<p class="MsoNormal">Dear All,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I'd like to get you feedback about change in BranchProbabilityInfo.<o:p></o:p></p>
<p class="MsoNormal">Specifically whether the proposed change makes sense and whether it<o:p></o:p></p>
<p class="MsoNormal">might cause some negative impact.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Currently the BranchProbabilityInfo contains a bunch of heuristics<o:p></o:p></p>
<p class="MsoNormal">which does not follow the restriction that sum of all branch probabilities<o:p></o:p></p>
<p class="MsoNormal"><span lang="RU">are equal to 1. This is due to denominator is fixed to 0x80000000 in<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="RU">BranchProbability class. As a result the probaility of 1 is expressed as<o:p></o:p></span></p>
<p class="MsoNormal">numerator 0x80000000. If we have three branches with equal weight then<o:p></o:p></p>
<p class="MsoNormal">it cannot be represented as integer value due to 0x80000000 / 3 = 0x2AAAAAAA * 3 + 2.<o:p></o:p></p>
<p class="MsoNormal">This remainder 2 is always less than number of branches. <span lang="RU">
In all current<o:p></o:p></span></p>
<p class="MsoNormal">heuristics this remainder just ignored.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">So the question is whether it makes sense to split this remainder between<o:p></o:p></p>
<p class="MsoNormal">first several branches or it is better just to drop it.<o:p></o:p></p>
<p class="MsoNormal">Note that if we distribute this remainder between some branches we can loose<o:p></o:p></p>
<p class="MsoNormal">the "precise" information that two branches has the same probability.<o:p></o:p></p>
<p class="MsoNormal">They will be slightly different due to we add 1 to some branches numerators.<o:p></o:p></p>
<p class="MsoNormal">So the second question is whether the loosing information about equality of<o:p></o:p></p>
<p class="MsoNormal">probabilities might have some negative impact so we should not do this change.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">The second question is as follows: currently BranchProbability operates on<o:p></o:p></p>
<p class="MsoNormal"><span lang="RU">weights but produces probabilites. For me personally it is cleaner if huristics<o:p></o:p></span></p>
<p class="MsoNormal">takes probabilities as input (except metadata heuristic). <o:p>
</o:p></p>
<p class="MsoNormal">Does it make sense to move from weights to probabilities in internal constants<o:p></o:p></p>
<p class="MsoNormal"><span lang="RU">used in BranchProbabilityInfo class. I do not have strong preference here,<o:p></o:p></span></p>
<p class="MsoNormal">so want to get your feedback.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Would appreciate for any feedback.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Thank you,<o:p></o:p></p>
<p class="MsoNormal">Serguei.<o:p></o:p></p>
<p class="MsoNormal"><span lang="RU"><o:p> </o:p></span></p>
</div>
</body>
</html>