例句與造句

1. A discrete symmetry group is a symmetry group that is a discrete isometry group.
2. A "'discrete symmetry group "'is a symmetry group such that for every point of the space the set of images of the point under the isometries in the symmetry group is a discrete set.
3. Discrete symmetry groups come in three types : ( 1 ) finite "'point groups "', which include only rotations, reflections, inversion and rotoinversion  they are just the finite subgroups of O ( " n " ), ( 2 ) infinite "'categorization of subgroups of the Euclidean group corresponds a categorization of symmetry groups.
4. It's difficult to find discrete symmetry group in a sentence. 用discrete symmetry group造句挺難的