Lightly Documented Features: Difference between revisions

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{{HelpLine|
{{HelpLine|
n = 1 |
n = 2 |
in = <nowiki>NumberOfKnots</nowiki> |
in = <nowiki>NumberOfKnots</nowiki> |
out= <nowiki>NumberOfKnots[n] returns the number of knots with n crossings.
out= <nowiki>NumberOfKnots[n] returns the number of knots with n crossings.
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{{InOut|
{{InOut|
n = 2 |
n = 3 |
in = <nowiki>NumberOfKnots[16, NonAlternating]</nowiki> |
in = <nowiki>NumberOfKnots[16, NonAlternating]</nowiki> |
out= <nowiki>1008906</nowiki>}}
out= <nowiki>1008906</nowiki>}}
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{{HelpLine|
{{HelpLine|
n = 3 |
n = 4 |
in = <nowiki>AlternatingQ</nowiki> |
in = <nowiki>AlternatingQ</nowiki> |
out= <nowiki>AlternatingQ[K] tries to decide if the knot K is alternating. This function is extremely incomplete; it only works for named knots from the tables, or torus knots.</nowiki>}}
out= <nowiki>AlternatingQ[D] returns True iff the knot/link diagram D is alternating.</nowiki>}}
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{{InOut|
{{InOut|
n = 4 |
n = 5 |
in = <nowiki>Total[AlternatingQ /@ AllKnots[{0,11}]]</nowiki> |
in = <nowiki>Total[AlternatingQ /@ AllKnots[{0,11}]]</nowiki> |
out= <nowiki>238 False + 564 True</nowiki>}}
out= <nowiki>238 False + 564 True</nowiki>}}

Latest revision as of 17:24, 21 February 2013


(For In[1] see Setup)

In[2]:= ?NumberOfKnots
NumberOfKnots[n] returns the number of knots with n crossings. NumberOfKnots[n, Alternating|NonAlternating] returns the number of knots of the specified type.
In[3]:= NumberOfKnots[16, NonAlternating]
Out[3]= 1008906
In[4]:= ?AlternatingQ
AlternatingQ[D] returns True iff the knot/link diagram D is alternating.

Among the knots with up to 11 crossings, 564 are alternating and 238 are not:

In[5]:= Total[AlternatingQ /@ AllKnots[{0,11}]]
Out[5]= 238 False + 564 True