Combination product set: Difference between revisions
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Wikispaces>xenwolf **Imported revision 150759453 - Original comment: oops I used the wrong wiki syntax** |
Wikispaces>genewardsmith **Imported revision 150760377 - 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:genewardsmith|genewardsmith]] and made on <tt>2010-06-28 04:10:35 UTC</tt>.<br> | ||
: The original revision id was <tt> | : The original revision id was <tt>150760377</tt>.<br> | ||
: The revision comment was: <tt> | : 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> | ||
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# The resulting elements are reduced to an octave and sorted in ascending order, resulting in an octave period of a [[periodic scale]] (the usual sort of scale, in other words.) | # The resulting elements are reduced to an octave and sorted in ascending order, resulting in an octave period of a [[periodic scale]] (the usual sort of scale, in other words.) | ||
This is sometimes called | This is sometimes called a k)n cps. There are special names for special cases: a 2)4 cps is called a [[hexany]]; both 2)5 and 3)5 cps are called dekanies; both 2)6 and 4)6 cps are called pentadekanies, and a 3)6 cps an eikosany. These are normally considered in connection with just intonation, so that the starting set is a set of positive rational numbers, but nothing prevents consideration of the more general case. | ||
The idea can be further generalized so that the thing we start from is not a set but a [[http://en.wikipedia.org/wiki/Multiset|multiset]]. A multiset is like a set, but the elements have multiplicites; there can be two, three or any number of a given kind of element. Submultisets of a multiset are also multisets, and the product over a multiset takes account of multiplicity. Hence the 2)4 hexany resulting from the multiset [1,1,3,5] first generates the two-element submultisets, which are [1, 1], [1, 3], [1, 5], [3, 5], and we obtain products 1, 3, 5, and 15. Reducing to an octave gives 5/4, 3/2, 15/8, 2 which can be transposed to 5/4, 4/3, 5/3, 2. In spite of being called a hexany it has only four notes. | The idea can be further generalized so that the thing we start from is not a set but a [[http://en.wikipedia.org/wiki/Multiset|multiset]]. A multiset is like a set, but the elements have multiplicites; there can be two, three or any number of a given kind of element. Submultisets of a multiset are also multisets, and the product over a multiset takes account of multiplicity. Hence the 2)4 hexany resulting from the multiset [1,1,3,5] first generates the two-element submultisets, which are [1, 1], [1, 3], [1, 5], [3, 5], and we obtain products 1, 3, 5, and 15. Reducing to an octave gives 5/4, 3/2, 15/8, 2 which can be transposed to 5/4, 4/3, 5/3, 2. In spite of being called a hexany it has only four notes. | ||
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<ol><li>A set of n positive real numbers is the starting point.</li><li>All the combinations of k elements of the set are obtained, and their products taken.</li><li>These are combined into a set, and then all of the elements of that set are divided by one of them (which one is arbitary.)</li><li>The resulting elements are reduced to an octave and sorted in ascending order, resulting in an octave period of a <a class="wiki_link" href="/periodic%20scale">periodic scale</a> (the usual sort of scale, in other words.)</li></ol><br /> | <ol><li>A set of n positive real numbers is the starting point.</li><li>All the combinations of k elements of the set are obtained, and their products taken.</li><li>These are combined into a set, and then all of the elements of that set are divided by one of them (which one is arbitary.)</li><li>The resulting elements are reduced to an octave and sorted in ascending order, resulting in an octave period of a <a class="wiki_link" href="/periodic%20scale">periodic scale</a> (the usual sort of scale, in other words.)</li></ol><br /> | ||
This is sometimes called | This is sometimes called a k)n cps. There are special names for special cases: a 2)4 cps is called a <a class="wiki_link" href="/hexany">hexany</a>; both 2)5 and 3)5 cps are called dekanies; both 2)6 and 4)6 cps are called pentadekanies, and a 3)6 cps an eikosany. These are normally considered in connection with just intonation, so that the starting set is a set of positive rational numbers, but nothing prevents consideration of the more general case.<br /> | ||
<br /> | <br /> | ||
The idea can be further generalized so that the thing we start from is not a set but a <a class="wiki_link_ext" href="http://en.wikipedia.org/wiki/Multiset" rel="nofollow">multiset</a>. A multiset is like a set, but the elements have multiplicites; there can be two, three or any number of a given kind of element. Submultisets of a multiset are also multisets, and the product over a multiset takes account of multiplicity. Hence the 2)4 hexany resulting from the multiset [1,1,3,5] first generates the two-element submultisets, which are [1, 1], [1, 3], [1, 5], [3, 5], and we obtain products 1, 3, 5, and 15. Reducing to an octave gives 5/4, 3/2, 15/8, 2 which can be transposed to 5/4, 4/3, 5/3, 2. In spite of being called a hexany it has only four notes.<br /> | The idea can be further generalized so that the thing we start from is not a set but a <a class="wiki_link_ext" href="http://en.wikipedia.org/wiki/Multiset" rel="nofollow">multiset</a>. A multiset is like a set, but the elements have multiplicites; there can be two, three or any number of a given kind of element. Submultisets of a multiset are also multisets, and the product over a multiset takes account of multiplicity. Hence the 2)4 hexany resulting from the multiset [1,1,3,5] first generates the two-element submultisets, which are [1, 1], [1, 3], [1, 5], [3, 5], and we obtain products 1, 3, 5, and 15. Reducing to an octave gives 5/4, 3/2, 15/8, 2 which can be transposed to 5/4, 4/3, 5/3, 2. In spite of being called a hexany it has only four notes.<br /> | ||
<br /> | <br /> | ||
Cps are closely related to <a class="wiki_link" href="/Euler%20genera">Euler genera</a>, since if we combine 0)n, 1)n, 2)n ... n)n before reducing to an octave, and then reduce, we get an Euler genus.</body></html></pre></div> | Cps are closely related to <a class="wiki_link" href="/Euler%20genera">Euler genera</a>, since if we combine 0)n, 1)n, 2)n ... n)n before reducing to an octave, and then reduce, we get an Euler genus.</body></html></pre></div> | ||
Revision as of 04:10, 28 June 2010
IMPORTED REVISION FROM WIKISPACES
This is an imported revision from Wikispaces. The revision metadata is included below for reference:
- This revision was by author genewardsmith and made on 2010-06-28 04:10:35 UTC.
- The original revision id was 150760377.
- The revision comment was:
The revision contents are below, presented both in the original Wikispaces Wikitext format, and in HTML exactly as Wikispaces rendered it.
Original Wikitext content:
A **combination product set** is a [[scale]] generated by the following means: # A set of n positive real numbers is the starting point. # All the combinations of k elements of the set are obtained, and their products taken. # These are combined into a set, and then all of the elements of that set are divided by one of them (which one is arbitary.) # The resulting elements are reduced to an octave and sorted in ascending order, resulting in an octave period of a [[periodic scale]] (the usual sort of scale, in other words.) This is sometimes called a k)n cps. There are special names for special cases: a 2)4 cps is called a [[hexany]]; both 2)5 and 3)5 cps are called dekanies; both 2)6 and 4)6 cps are called pentadekanies, and a 3)6 cps an eikosany. These are normally considered in connection with just intonation, so that the starting set is a set of positive rational numbers, but nothing prevents consideration of the more general case. The idea can be further generalized so that the thing we start from is not a set but a [[http://en.wikipedia.org/wiki/Multiset|multiset]]. A multiset is like a set, but the elements have multiplicites; there can be two, three or any number of a given kind of element. Submultisets of a multiset are also multisets, and the product over a multiset takes account of multiplicity. Hence the 2)4 hexany resulting from the multiset [1,1,3,5] first generates the two-element submultisets, which are [1, 1], [1, 3], [1, 5], [3, 5], and we obtain products 1, 3, 5, and 15. Reducing to an octave gives 5/4, 3/2, 15/8, 2 which can be transposed to 5/4, 4/3, 5/3, 2. In spite of being called a hexany it has only four notes. Cps are closely related to [[Euler genera]], since if we combine 0)n, 1)n, 2)n ... n)n before reducing to an octave, and then reduce, we get an Euler genus.
Original HTML content:
<html><head><title>Combination product sets</title></head><body>A <strong>combination product set</strong> is a <a class="wiki_link" href="/scale">scale</a> generated by the following means:<br /> <br /> <ol><li>A set of n positive real numbers is the starting point.</li><li>All the combinations of k elements of the set are obtained, and their products taken.</li><li>These are combined into a set, and then all of the elements of that set are divided by one of them (which one is arbitary.)</li><li>The resulting elements are reduced to an octave and sorted in ascending order, resulting in an octave period of a <a class="wiki_link" href="/periodic%20scale">periodic scale</a> (the usual sort of scale, in other words.)</li></ol><br /> This is sometimes called a k)n cps. There are special names for special cases: a 2)4 cps is called a <a class="wiki_link" href="/hexany">hexany</a>; both 2)5 and 3)5 cps are called dekanies; both 2)6 and 4)6 cps are called pentadekanies, and a 3)6 cps an eikosany. These are normally considered in connection with just intonation, so that the starting set is a set of positive rational numbers, but nothing prevents consideration of the more general case.<br /> <br /> The idea can be further generalized so that the thing we start from is not a set but a <a class="wiki_link_ext" href="http://en.wikipedia.org/wiki/Multiset" rel="nofollow">multiset</a>. A multiset is like a set, but the elements have multiplicites; there can be two, three or any number of a given kind of element. Submultisets of a multiset are also multisets, and the product over a multiset takes account of multiplicity. Hence the 2)4 hexany resulting from the multiset [1,1,3,5] first generates the two-element submultisets, which are [1, 1], [1, 3], [1, 5], [3, 5], and we obtain products 1, 3, 5, and 15. Reducing to an octave gives 5/4, 3/2, 15/8, 2 which can be transposed to 5/4, 4/3, 5/3, 2. In spite of being called a hexany it has only four notes.<br /> <br /> Cps are closely related to <a class="wiki_link" href="/Euler%20genera">Euler genera</a>, since if we combine 0)n, 1)n, 2)n ... n)n before reducing to an octave, and then reduce, we get an Euler genus.</body></html>