07.04.2013 Views

Knot theory exercise sheet - week V (1) Determine the colouring ...

Knot theory exercise sheet - week V (1) Determine the colouring ...

Knot theory exercise sheet - week V (1) Determine the colouring ...

SHOW MORE
SHOW LESS

Create successful ePaper yourself

Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.

<strong>Knot</strong> <strong><strong>the</strong>ory</strong> <strong>exercise</strong> <strong>sheet</strong> - <strong>week</strong> V<br />

(1) <strong>Determine</strong> <strong>the</strong> <strong>colouring</strong> group for any 4 non-trivial knots from<br />

<strong>the</strong> table.<br />

(2) <strong>Determine</strong> <strong>the</strong> <strong>colouring</strong> group for <strong>the</strong> Hopf link, Whitehead<br />

link and <strong>the</strong> Borromean rings. What is <strong>the</strong> determinant of<br />

<strong>the</strong>se links?<br />

(3) <strong>Determine</strong> <strong>the</strong> <strong>colouring</strong> group of <strong>the</strong> following knot<br />

Can you identify this knot in <strong>the</strong> table of knots? What is<br />

<strong>the</strong> determinant of this knot?<br />

(4) Give an example of a knot or a link with <strong>the</strong> <strong>colouring</strong> group<br />

isomorphic to:<br />

(a) Z<br />

(b) Z 2<br />

(c) Z n<br />

(d) Z/3<br />

(e) Z/5<br />

(f) Z/7<br />

(g) Z/p, where p is a prime number.<br />

(h) Z/3 ⊕ Z/5<br />

(i) Z/15<br />

(j) Z/2<br />

(5) Calculate <strong>the</strong> Alexander polynomial for <strong>the</strong> figure eight knot, a<br />

knot with 7, 8 and 9 crossings and for <strong>the</strong> knots 3 1, 5 1, 7 1<br />

and 9 1.<br />

(6) <strong>Determine</strong> <strong>the</strong> Alexander polynomial for <strong>the</strong> Borromean rings.<br />

1


2<br />

(7) Is <strong>the</strong> following link splitable?<br />

(8) Express <strong>the</strong> following knot as <strong>the</strong> sum of prime knots and determine<br />

its Alexander polynomial.<br />

(9) Suppose that <strong>the</strong> polynomial t 4 +5t 3 +5t 2 +5t+5 is <strong>the</strong> Alexander<br />

polynomial of a knot K. Is K prime?

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!