论文标题
定向保留和定向的映射的新公式
A new formulation of the semigroup of orientation-preserving and orientation-reversing mappings
论文作者
论文摘要
我们根据其对定向三元组和定向四倍体的行动来表征保留有限循环的映射的各自的映射的半群。这导致了证据，即后者的半群与所有映射的半群相吻合，这些映射保留了相应圆圈上和弦的交叉点。
We characterize the respective semigroups of mappings that preserve, or that preserve or reverse orientation of a finite cycle, in terms of their actions on oriented triples and oriented quadruples. This leads to a proof that the latter semigroup coincides with the semigroup of all mappings that preserve intersections of chords on the corresponding circle.
