Calabi--Yau 3-folds

This section describes intrinsics that construct Calabi--Yau 3-folds. It also describes a few intrinsics that can be used to study them, but see Section Generic Polarised Varieties for the general intrinsics that apply to all polarised varieties.

The calculations are based on Buckley's Riemann--Roch formula [Buc03] for polarised Calabi--Yau 3-folds with canonical singularities.

CalabiYau(p1,p2,B) : RngIntElt,RngIntElt,GRBskt -> GRCY
The Calabi--Yau 3-fold X, A with h0(X, A)=p1, h0(X, 2A)=p2 and basket of singularities B.
FindN(X) : GRCY -> RngIntElt,RngIntElt
    MaximumN: RngIntElt                 Default: 100
The first nonnegative value, for the Calabi--Yau 3-fold X, of NCi (where Ci is the ith curve of the basket of X) together with the distance between successive values of NCi. (The pair 0, 0 is returned if no solutions below the parameter MaximumN are found).
FindN(p1,p2,B) : RngIntElt,RngIntElt,GRBskt -> RngIntElt,RngIntElt
    MaximumN: RngIntElt                 Default: 100
The first nonnegative value of NCi (where Ci is the ith curve of the basket B of 3-fold points and curves and p1, p2 are the first two genera) together with the distance between successive values of NCi. (The pair 0, 0 is returned if no solutions below the parameter MaximumN are found).
V2.28, 13 July 2023