The Determinant and the Signature: Difference between revisions

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{{Startup Note}}
{{Startup Note}}
<!--$$?KnotDet$$-->
<!--$$?KnotDet$$-->
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{{Help1|n=2|s=KnotDet}}
{{Help1|n=1|s=KnotDet}}
KnotDet[K] returns the determinant of a knot K.
KnotDet[K] returns the determinant of a knot K.
{{Help2}}
{{Help2}}
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<!--$$?KnotSignature$$-->
<!--$$?KnotSignature$$-->
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{{Help1|n=3|s=KnotSignature}}
{{Help1|n=2|s=KnotSignature}}
KnotSignature[K] returns the signature of a knot K.
KnotSignature[K] returns the signature of a knot K.
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{{Help2}}
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<!--$$KnotDet /@ {Knot[5, 1], Knot[10, 132]}$$-->
<!--$$KnotDet /@ {Knot[5, 1], Knot[10, 132]}$$-->
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{{InOut1|n=4}}
{{InOut1|n=3}}
KnotDet /@ {Knot[5, 1], Knot[10, 132]}
<pre style="color: red; border: 0px; padding: 0em"><nowiki>KnotDet /@ {Knot[5, 1], Knot[10, 132]}</nowiki></pre>
{{InOut2|n=4}}<pre style="border: 0px; padding: 0em"><nowiki>{5, 5}</nowiki></pre>
{{InOut2|n=3}}<pre style="border: 0px; padding: 0em"><nowiki>{5, 5}</nowiki></pre>
{{InOut3}}
{{InOut3}}
<!--END-->
<!--END-->


<!--$${Equal @@ (Jones[#][q]& /@ {Knot[5, 1], Knot[10, 132]}), Equal @@ (Alexander[#][t]& /@ {Knot[5, 1], Knot[10, 132]})}$$-->
<!--$${Equal @@ (Jones[#][q]& /@ {Knot[5, 1], Knot[10, 132]}), Equal @@ (Alexander[#][t]& /@ {Knot[5, 1], Knot[10, 132]})}$$-->
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{{InOut1|n=5}}
{{InOut1|n=4}}
{Equal @@ (Jones[#][q]& /@ {Knot[5, 1], Knot[10, 132]}), Equal @@ (Alexander[#][t]& /@ {Knot[5, 1], Knot[10, 132]})}
<pre style="color: red; border: 0px; padding: 0em"><nowiki>{Equal @@ (Jones[#][q]& /@ {Knot[5, 1], Knot[10, 132]}), Equal @@ (Alexander[#][t]& /@ {Knot[5, 1], Knot[10, 132]})}</nowiki></pre>
{{InOut2|n=5}}<pre style="border: 0px; padding: 0em"><nowiki>{True, True}</nowiki></pre>
{{InOut2|n=4}}<pre style="border: 0px; padding: 0em"><nowiki>{True, True}</nowiki></pre>
{{InOut3}}
{{InOut3}}
<!--END-->
<!--END-->


<!--$$KnotSignature /@ {Knot[5, 1], Knot[10, 132]}$$-->
<!--$$KnotSignature /@ {Knot[5, 1], Knot[10, 132]}$$-->
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{{InOut1|n=6}}
{{InOut1|n=5}}
KnotSignature /@ {Knot[5, 1], Knot[10, 132]}
<pre style="color: red; border: 0px; padding: 0em"><nowiki>KnotSignature /@ {Knot[5, 1], Knot[10, 132]}</nowiki></pre>
{{InOut2|n=6}}<pre style="border: 0px; padding: 0em"><nowiki>{-4, 0}</nowiki></pre>
{{InOut2|n=5}}<pre style="border: 0px; padding: 0em"><nowiki>{-4, 0}</nowiki></pre>
{{InOut3}}
{{InOut3}}
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Revision as of 19:43, 27 August 2005


(For In[1] see Setup)

In[1]:= ?KnotDet

KnotDet[K] returns the determinant of a knot K.

In[2]:= ?KnotSignature

KnotSignature[K] returns the signature of a knot K.

Thus, for example, the knots 5_1 and 10_132 have the same determinant (and even the same Alexander and Jones polynomials), but different signatures:

In[3]:=
KnotDet /@ {Knot[5, 1], Knot[10, 132]}
Out[3]=
{5, 5}
In[4]:=
{Equal @@ (Jones[#][q]& /@ {Knot[5, 1], Knot[10, 132]}), Equal @@ (Alexander[#][t]& /@ {Knot[5, 1], Knot[10, 132]})}
Out[4]=
{True, True}
In[5]:=
KnotSignature /@ {Knot[5, 1], Knot[10, 132]}
Out[5]=
{-4, 0}