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'''Multiexpansion '''refers to the function <math>a\ \{\{2\}\}\ b = \{a,b,2,2\} = \underbrace{a \{\{1\}\} a \{\{1\}\} \ldots \{\{1\}\} a \{\{1\}\} a}_b</math>, using [[BEAF]].<ref>[http://www.polytope.net/hedrondude/array.htm]</ref>
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'''Multiexpansion '''refers to the binary function \(a \{\{2\}\} b = \{a,b,2,2\} = \underbrace{a \{\{1\}\} a \{\{1\}\} \ldots \{\{1\}\} a \{\{1\}\} a}_{\text{b a's}}\) using [[BEAF]].<ref>[http://www.polytope.net/hedrondude/array.htm Array Notation by Jonathan Bowers]</ref>
   
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In the [[fast-growing hierarchy]], \(f_{\omega+2}(n)\) is comparable to multiexpandal growth rate, which means multiexpansion is comparable to \(a\rightarrow a\rightarrow b\rightarrow 3\) in [[Chained Arrow Notation]] and \((a\{3,3\}b)\) in [[Notation Array Notation]].
=== Sources ===
 
<references />
 
   
=== See also ===
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==Examples==
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*\(\{a,3,2,2\} = a\{\{1\}\}a\{\{1\}\}a\). This is equal to ''a'' expanded to (''a'' expanded to ''a''). Let \(A = a\{a\{a...a\{a\{a\}a\}a...a\}a\}a (a\ a's)\), then \(\{a,3,2,2\} = a\{a...a\{a\}a...a\}a (A\ a's)\)
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*\(\{3,2,2,2\} = 3\{\{2\}\}2 = 3\{\{1\}\}3 = \{3,3,1,2\}\)
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*\(\{4,2,2,2\} = \{4,4,1,2\}\)
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*\(\{3,3,2,2\} = 3\{\{2\}\}3 = 3\{\{1\}\}3\{\{1\}\}3 = \{3,\{3,3,1,2\},1,2\}\)
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*\(\{6,4,2,2\} = 6\{\{2\}\}4 = 6\{\{1\}\}6\{\{1\}\}6\{\{1\}\}6 = \{6,\{6,\{6,6,1,2\},1,2\},1,2\}\)
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== Pseudocode ==
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Below is an example of pseudocode for multiexpansion.
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'''function''' multiexpansion(''a'', ''b''):
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''result'' := ''a''
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'''repeat''' ''b'' - 1 '''times''':
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'''result''' := expansion(''a'', ''result'')
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'''return''' ''result''
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'''function''' expansion(''a'', ''b''):
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''result'' := ''a''
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'''repeat''' ''b'' - 1 '''times''':
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'''result''' := hyper(''a'', ''a'', ''result'' + 2)
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'''return''' ''result''
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'''function''' hyper(''a'', ''b'', ''n''):
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'''if''' ''n'' = 1:
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'''return''' ''a'' + ''b''
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''result'' := ''a''
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'''repeat''' ''b'' - 1 '''times''':
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''result'' := hyper(''a'', ''result'', ''n'' - 1)
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'''return''' ''result''
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== Sources ==
 
<references />
   
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== See also ==
 
{{ExtendedOps}}
 
{{ExtendedOps}}
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[[ja:乗算膨張]]
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[[zh:Multiexpansion]]
 
[[Category:Functions]]
 
[[Category:Functions]]
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[[Category:Binary operators]]
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[[Category:BEAF]]
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[[Category:Jonathan Bowers]]
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[[Category:Extended hyper operators]]

Revision as of 00:51, 28 November 2020

Multiexpansion refers to the binary function \(a \{\{2\}\} b = \{a,b,2,2\} = \underbrace{a \{\{1\}\} a \{\{1\}\} \ldots \{\{1\}\} a \{\{1\}\} a}_{\text{b a's}}\) using BEAF.[1]

In the fast-growing hierarchy, \(f_{\omega+2}(n)\) is comparable to multiexpandal growth rate, which means multiexpansion is comparable to \(a\rightarrow a\rightarrow b\rightarrow 3\) in Chained Arrow Notation and \((a\{3,3\}b)\) in Notation Array Notation.

Examples

  • \(\{a,3,2,2\} = a\{\{1\}\}a\{\{1\}\}a\). This is equal to a expanded to (a expanded to a). Let \(A = a\{a\{a...a\{a\{a\}a\}a...a\}a\}a (a\ a's)\), then \(\{a,3,2,2\} = a\{a...a\{a\}a...a\}a (A\ a's)\)
  • \(\{3,2,2,2\} = 3\{\{2\}\}2 = 3\{\{1\}\}3 = \{3,3,1,2\}\)
  • \(\{4,2,2,2\} = \{4,4,1,2\}\)
  • \(\{3,3,2,2\} = 3\{\{2\}\}3 = 3\{\{1\}\}3\{\{1\}\}3 = \{3,\{3,3,1,2\},1,2\}\)
  • \(\{6,4,2,2\} = 6\{\{2\}\}4 = 6\{\{1\}\}6\{\{1\}\}6\{\{1\}\}6 = \{6,\{6,\{6,6,1,2\},1,2\},1,2\}\)

Pseudocode

Below is an example of pseudocode for multiexpansion.

function multiexpansion(a, b):
    result := a
    repeat b - 1 times:
        result := expansion(a, result)
    return result

function expansion(a, b):
    result := a
    repeat b - 1 times:
        result := hyper(a, a, result + 2)
    return result

function hyper(a, b, n):
    if n = 1:
        return a + b
    result := a
    repeat b - 1 times:
        result := hyper(a, result, n - 1)
    return result

Sources

See also