next | previous | forward | backward | up | top | index | toc | Macaulay2 web site
RandomGenus14Curves :: randomCanonicalCurveGenus8with8Points

randomCanonicalCurveGenus8with8Points -- Compute a random canonical curve of genus 8 with 8 marked point

Synopsis

Description

According to Mukai [Mu] any smooth curve of genus 8 and Clifford index 3 is the transversal intersection C=ℙ7 ∩ G(2,6) ⊂ ℙ15. In particular this is true for the general curve of genus 8. Picking 8 points in the Grassmannian G(2,6) at random and ℙ7 as their span gives the result.

i1 : FF=ZZ/10007;S=FF[x_0..x_7];
i3 : (I,points)=randomCanonicalCurveGenus8with8Points S;
i4 : betti res I

            0  1  2  3  4  5 6
o4 = total: 1 15 35 42 35 15 1
         0: 1  .  .  .  .  . .
         1: . 15 35 21  .  . .
         2: .  .  . 21 35 15 .
         3: .  .  .  .  .  . 1

o4 : BettiTally
i5 : points

o5 = {ideal (x  + 2776x , x  - 1893x , x  - 1851x , x  + 917x , x  - 4266x ,
              6        7   5        7   4        7   3       7   2        7 
     ------------------------------------------------------------------------
     x  + 1148x , x  + 1523x ), ideal (x  + 1549x , x  - 831x , x  - 781x ,
      1        7   0        7           6        7   5       7   4       7 
     ------------------------------------------------------------------------
     x  - 3305x , x  + 69x , x  - 2610x , x  + 732x ), ideal (x  - 2145x , x 
      3        7   2      7   1        7   0       7           6        7   5
     ------------------------------------------------------------------------
     - 2833x , x  + 1040x , x  + 1470x , x  + 591x , x  + 2183x , x  -
            7   4        7   3        7   2       7   1        7   0  
     ------------------------------------------------------------------------
     4856x ), ideal (x  + 1900x , x  - 2964x , x  - 747x , x  + 129x , x  -
          7           6        7   5        7   4       7   3       7   2  
     ------------------------------------------------------------------------
     3749x , x  + 3747x , x  + 385x ), ideal (x  - 4122x , x  - 2329x , x  -
          7   1        7   0       7           6        7   5        7   4  
     ------------------------------------------------------------------------
     3768x , x  + 446x , x  - 596x , x  - 511x , x  - 105x ), ideal (x  -
          7   3       7   2       7   1       7   0       7           6  
     ------------------------------------------------------------------------
     3504x , x  + 807x , x  - 1269x , x  - 11x , x  - 477x , x  + 2179x , x 
          7   5       7   4        7   3      7   2       7   1        7   0
     ------------------------------------------------------------------------
     - 3206x ), ideal (x  + 3353x , x  + 1385x , x  + 3198x , x  - 4928x , x 
            7           6        7   5        7   4        7   3        7   2
     ------------------------------------------------------------------------
     - 4609x , x  - 3236x , x  - 2724x ), ideal (x  + 475x , x  + 2585x , x 
            7   1        7   0        7           6       7   5        7   4
     ------------------------------------------------------------------------
     - 2359x , x  - 4050x , x  - 4366x , x  + 2113x , x  + 1037x )}
            7   3        7   2        7   1        7   0        7

o5 : List

Ways to use randomCanonicalCurveGenus8with8Points :

  • randomCanonicalCurveGenus8with8Points(PolynomialRing)