coefficientRing(LatticePolarizedK3surface) -- coefficient ring of a K3 surface

i1 : K = ZZ/3331

o1 = K

o1 : QuotientRing

i2 : S = K3(5,2,-2,CoefficientRing=>K)

o2 = K3 surface with rank 2 lattice defined by the intersection matrix: | 8 2  |
                                                                        | 2 -2 |
     -- (1,0): K3 surface of genus 5 and degree 8 containing rational curve of degree 2 
     -- (2,0): K3 surface of genus 17 and degree 32 containing rational curve of degree 4 
     -- (2,1): K3 surface of genus 20 and degree 38 containing rational curve of degree 2 (cubic fourfold) 
     -- (3,0): K3 surface of genus 37 and degree 72 containing rational curve of degree 6 
     -- (3,1): K3 surface of genus 42 and degree 82 containing rational curve of degree 4 (GM fourfold) 


o2 : Lattice-polarized K3 surface

i3 : coefficientRing S

o3 = K

o3 : QuotientRing