Arf Invariant

Author

Eric W. Weisstein
July 10, 2007

This notebook downloaded from http://mathworld.wolfram.com/notebooks/KnotTheory/ArfInvariant.nb.

For more information, see Eric's MathWorld entry http://mathworld.wolfram.com/ArfInvariant.html.

©2007 Wolfram Research, Inc. except for portions noted otherwise

Examples

Grid[KnotData[#,{"Name","ArfInvariant"}]&/@KnotData[],Dividers->All,Alignment->{Left,Center}]

DeleteCases[{#,KnotData[#,"ArfInvariant"]}&/@KnotData[All],{_,0|1}]

l=Table[{#,KnotData[#,"ArfInvariant"]}&/@Cases[KnotData[All],{n,_}],{n,10}]

a0=Count[#,{_,0}]&/@l

a1=Count[#,{_,1}]&/@l

a0+a1

Table[Count[KnotData[All],{n,_}],{n,10}]