Height: Difference between revisions

Wikispaces>mbattaglia1
**Imported revision 447782290 - Original comment: **
Wikispaces>genewardsmith
**Imported revision 447860730 - 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:mbattaglia1|mbattaglia1]] and made on <tt>2013-08-31 06:53:49 UTC</tt>.<br>
: This revision was by author [[User:genewardsmith|genewardsmith]] and made on <tt>2013-08-31 20:57:07 UTC</tt>.<br>
: The original revision id was <tt>447782290</tt>.<br>
: The original revision id was <tt>447860730</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>
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# 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.
# H(q) is bounded below by H(1), so that H(q) ≥ H(1) for all q.
# H(q) is bounded below by H(1), so that H(q) ≥ H(1) for all q.
# H(q) = H(1) iff q = 1.
# H(q) = H(1/q)
# H(q) = H(1/q)
# H(q^n) ≥ H(q) for any non-negative integer n
# H(q^n) ≥ H(q) for any non-negative integer n
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[[math]]
[[math]]


A **semi-height** is a function which does not obey criteria #1 above in the strictest sense, so that there is a rational number q ≠ 1 such that H(q) = H(1), resulting in an equivalence relation on its elements. An example would be octave-equivalence, where two ratios p and q are considered equivalent if the following is true:
A **semi-height** is a function which does not obey criteria #3 above in the strictest sense, so that there is a rational number q ≠ 1 such that H(q) = H(1), resulting in an equivalence relation on its elements. An example would be octave-equivalence, where two ratios p and q are considered equivalent if the following is true:
[[math]]
[[math]]
2^{-v_2 \left( {p} \right)} p = 2^{-v_2 \left( {q} \right)} q
2^{-v_2 \left( {p} \right)} p = 2^{-v_2 \left( {q} \right)} q
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&lt;br /&gt;
&lt;br /&gt;
A height function H(q) on the positive rationals q should fulfill the following criteria:&lt;br /&gt;
A height function H(q) on the positive rationals q should fulfill the following criteria:&lt;br /&gt;
&lt;ol&gt;&lt;li&gt;Given any constant C, there are finitely many elements q such that H(q) ≤ C.&lt;/li&gt;&lt;li&gt;H(q) is bounded below by H(1), so that H(q) ≥ H(1) for all q.&lt;/li&gt;&lt;li&gt;H(q) = H(1/q)&lt;/li&gt;&lt;li&gt;H(q^n) ≥ H(q) for any non-negative integer n&lt;/li&gt;&lt;/ol&gt;&lt;br /&gt;
&lt;ol&gt;&lt;li&gt;Given any constant C, there are finitely many elements q such that H(q) ≤ C.&lt;/li&gt;&lt;li&gt;H(q) is bounded below by H(1), so that H(q) ≥ H(1) for all q.&lt;/li&gt;&lt;li&gt;H(q) = H(1) iff q = 1.&lt;/li&gt;&lt;li&gt;H(q) = H(1/q)&lt;/li&gt;&lt;li&gt;H(q^n) ≥ H(q) for any non-negative integer n&lt;/li&gt;&lt;/ol&gt;&lt;br /&gt;
If we have a function F(x) which is strictly increasing on the positive reals, then F(H(q)) will rank elements in the same order as H(q). We can therefore establish the following equivalence relation:&lt;br /&gt;
If we have a function F(x) which is strictly increasing on the positive reals, then F(H(q)) will rank elements in the same order as H(q). We can therefore establish the following equivalence relation:&lt;br /&gt;
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  --&gt;&lt;script type="math/tex"&gt;H \left( {q} \right) \equiv F \left( {H} \left( {q} \right) \right)&lt;/script&gt;&lt;!-- ws:end:WikiTextMathRule:0 --&gt;&lt;br /&gt;
  --&gt;&lt;script type="math/tex"&gt;H \left( {q} \right) \equiv F \left( {H} \left( {q} \right) \right)&lt;/script&gt;&lt;!-- ws:end:WikiTextMathRule:0 --&gt;&lt;br /&gt;
&lt;br /&gt;
&lt;br /&gt;
A &lt;strong&gt;semi-height&lt;/strong&gt; is a function which does not obey criteria #1 above in the strictest sense, so that there is a rational number q ≠ 1 such that H(q) = H(1), resulting in an equivalence relation on its elements. An example would be octave-equivalence, where two ratios p and q are considered equivalent if the following is true:&lt;br /&gt;
A &lt;strong&gt;semi-height&lt;/strong&gt; is a function which does not obey criteria #3 above in the strictest sense, so that there is a rational number q ≠ 1 such that H(q) = H(1), resulting in an equivalence relation on its elements. An example would be octave-equivalence, where two ratios p and q are considered equivalent if the following is true:&lt;br /&gt;
&lt;!-- ws:start:WikiTextMathRule:1:
&lt;!-- ws:start:WikiTextMathRule:1:
[[math]]&amp;lt;br/&amp;gt;
[[math]]&amp;lt;br/&amp;gt;