??ideal class group of the laurent polynomials ...

??ideal class group of Z[1/3] ... ???...

??something about "branch point" here ??? .... ????....

???ideal class group of Q ... ????....

??absolute galois group of Q ... ????....

ideal class group of ... ???...




??divisor class group of dense open affine subvariety of elliptic curve ... ??...

??"zariski topology hasn't got enough open sets... use coverings instead ..." ... ???or something ... ???....