example

gistfile1.txt

sage: L = link.Link(oriented_gauss_code = [[-1, +2, -3, 4, +5, +1, -2, +6, +7, 3, -4, -7, -6,-5],['-','-','-','-','+','-','+']])
sage: L.PD_code()
[[1, 7, 2, 6],
 [7, 3, 8, 2],
 [3, 11, 4, 10],
 [11, 5, 12, 4],
 [14, 5, 1, 6],
 [13, 9, 14, 8],
 [12, 9, 13, 10]]
sage: e = [[1, 7, 2, 6],
....:  [7, 3, 8, 2],
....:  [3, 11, 4, 10],
....:  [11, 5, 12, 4],
....:  [14, 5, 1, 6],
....:  [13, 9, 14, 8],
....:  [12, 9, 13, 10]]
sage: L = link.Link(PD_code = e)
sage: L.remove_regions()
[[1, 9, 2, 8],
 [9, 3, 10, 2],
 [5, 13, 6, 12],
 [13, 7, 14, 6],
 [18, 7, 1, 8],
 [17, 11, 18, 10],
 [14, 11, 15, 12],
 [16, 4, 17, 3],
 [15, 4, 16, 5]]
sage: e = [[1, 9, 2, 8],
....:  [9, 3, 10, 2],
....:  [5, 13, 6, 12],
....:  [13, 7, 14, 6],
....:  [18, 7, 1, 8],
....:  [17, 11, 18, 10],
....:  [14, 11, 15, 12],
....:  [16, 4, 17, 3],
....:  [15, 4, 16, 5]]
sage: L = link.Link(PD_code = e)
sage: L.remove_regions()
[[1, 9, 2, 8],
 [9, 3, 10, 2],
 [5, 13, 6, 12],
 [13, 7, 14, 6],
 [22, 7, 1, 8],
 [19, 11, 20, 10],
 [16, 11, 17, 12],
 [18, 4, 19, 3],
 [17, 4, 18, 5],
 [21, 14, 22, 15],
 [20, 16, 21, 15]]
sage: e = [[1, 9, 2, 8],
....:  [9, 3, 10, 2],
....:  [5, 13, 6, 12],
....:  [13, 7, 14, 6],
....:  [22, 7, 1, 8],
....:  [19, 11, 20, 10],
....:  [16, 11, 17, 12],
....:  [18, 4, 19, 3],
....:  [17, 4, 18, 5],
....:  [21, 14, 22, 15],
....:  [20, 16, 21, 15]]
sage: L.remove_regions()
[[1, 9, 2, 8],
 [9, 3, 10, 2],
 [5, 13, 6, 12],
 [13, 7, 14, 6],
 [22, 7, 1, 8],
 [19, 11, 20, 10],
 [16, 11, 17, 12],
 [18, 4, 19, 3],
 [17, 4, 18, 5],
 [21, 14, 22, 15],
 [20, 16, 21, 15]]
sage: