Height: Difference between revisions
Wikispaces>guest **Imported revision 362749812 - Original comment: ** |
Wikispaces>Sarzadoce **Imported revision 363105768 - Original comment: ** |
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<h2>IMPORTED REVISION FROM WIKISPACES</h2> | <h2>IMPORTED REVISION FROM WIKISPACES</h2> | ||
This is an imported revision from Wikispaces. The revision metadata is included below for reference:<br> | This is an imported revision from Wikispaces. The revision metadata is included below for reference:<br> | ||
: This revision was by author [[User: | : This revision was by author [[User:Sarzadoce|Sarzadoce]] and made on <tt>2012-09-08 23:32:31 UTC</tt>.<br> | ||
: The original revision id was <tt> | : The original revision id was <tt>363105768</tt>.<br> | ||
: The revision comment was: <tt></tt><br> | : The revision comment was: <tt></tt><br> | ||
The revision contents are below, presented both in the original Wikispaces Wikitext format, and in HTML exactly as Wikispaces rendered it.<br> | The revision contents are below, presented both in the original Wikispaces Wikitext format, and in HTML exactly as Wikispaces rendered it.<br> | ||
<h4>Original Wikitext content:</h4> | <h4>Original Wikitext content:</h4> | ||
<div style="width:100%; max-height:400pt; overflow:auto; background-color:#f8f9fa; border: 1px solid #eaecf0; padding:0em"><pre style="margin:0px;border:none;background:none;word-wrap:break-word;white-space: pre-wrap ! important" class="old-revision-html">=Definition:= | <div style="width:100%; max-height:400pt; overflow:auto; background-color:#f8f9fa; border: 1px solid #eaecf0; padding:0em"><pre style="margin:0px;border:none;background:none;word-wrap:break-word;white-space: pre-wrap ! important" class="old-revision-html">=Definition:= | ||
A **height** is a function on an abelian group which maps elements to real numbers, yielding a type of complexity measurement. Since the | A **height** is a function on an abelian group which maps elements to real numbers, yielding a type of complexity measurement. Since the positive rationals form an abelian group under multiplication, we can assign each element a height, and hence a complexity. While there is no concensus on the restrictions of a height, we will attempt to create a definition which is practical for musical purposes. | ||
A height function H(q) on the rationals q should fulfill the following criteria: | A height function H(q) on the positive rationals q should fulfill the following criteria: | ||
# Given any constant C, there are finitely many elements q such that H(q) <= C. | # Given any constant C, there are finitely many elements q such that H(q) <= C. | ||
# There is a unique constant K such that H(q) >= K, for all q. | # There is a unique constant K such that H(q) >= K, for all q. | ||
# H(q) = H(1/q) | # H(q) = H(1/q) | ||
# H(q^n) >= H(q) for any non-negative integer n | |||
Since any rational q can be rewritten as a fraction n/d, we may sub this into the above equation to get H(n/d) = H(d/n). This relation is extremely useful - it tells us that we can switch n and d without any consequences on the outcome of the height. | Since any rational q can be rewritten as a fraction n/d, we may sub this into the above equation to get H(n/d) = H(d/n). This relation is extremely useful - it tells us that we can switch n and d without any consequences on the outcome of the height. | ||
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<h4>Original HTML content:</h4> | <h4>Original HTML content:</h4> | ||
<div style="width:100%; max-height:400pt; overflow:auto; background-color:#f8f9fa; border: 1px solid #eaecf0; padding:0em"><pre style="margin:0px;border:none;background:none;word-wrap:break-word;width:200%;white-space: pre-wrap ! important" class="old-revision-html"><html><head><title>Height</title></head><body><!-- ws:start:WikiTextHeadingRule:16:&lt;h1&gt; --><h1 id="toc0"><a name="Definition:"></a><!-- ws:end:WikiTextHeadingRule:16 -->Definition:</h1> | <div style="width:100%; max-height:400pt; overflow:auto; background-color:#f8f9fa; border: 1px solid #eaecf0; padding:0em"><pre style="margin:0px;border:none;background:none;word-wrap:break-word;width:200%;white-space: pre-wrap ! important" class="old-revision-html"><html><head><title>Height</title></head><body><!-- ws:start:WikiTextHeadingRule:16:&lt;h1&gt; --><h1 id="toc0"><a name="Definition:"></a><!-- ws:end:WikiTextHeadingRule:16 -->Definition:</h1> | ||
A <strong>height</strong> is a function on an abelian group which maps elements to real numbers, yielding a type of complexity measurement. Since the | A <strong>height</strong> is a function on an abelian group which maps elements to real numbers, yielding a type of complexity measurement. Since the positive rationals form an abelian group under multiplication, we can assign each element a height, and hence a complexity. While there is no concensus on the restrictions of a height, we will attempt to create a definition which is practical for musical purposes.<br /> | ||
<br /> | <br /> | ||
A height function H(q) on the rationals q should fulfill the following criteria:<br /> | A height function H(q) on the positive rationals q should fulfill the following criteria:<br /> | ||
<ol><li>Given any constant C, there are finitely many elements q such that H(q) &lt;= C.</li><li>There is a unique constant K such that H(q) &gt;= K, for all q.</li><li>H(q) = H(1/q)</li></ol><br /> | <ol><li>Given any constant C, there are finitely many elements q such that H(q) &lt;= C.</li><li>There is a unique constant K such that H(q) &gt;= K, for all q.</li><li>H(q) = H(1/q)</li><li>H(q^n) &gt;= H(q) for any non-negative integer n</li></ol><br /> | ||
Since any rational q can be rewritten as a fraction n/d, we may sub this into the above equation to get H(n/d) = H(d/n). This relation is extremely useful - it tells us that we can switch n and d without any consequences on the outcome of the height.<br /> | Since any rational q can be rewritten as a fraction n/d, we may sub this into the above equation to get H(n/d) = H(d/n). This relation is extremely useful - it tells us that we can switch n and d without any consequences on the outcome of the height.<br /> | ||
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