fact: Definition zstepL zp := match zp with | Zpart Zhub _ _ => zshiftl Zhubl zp | Zpart Zhubl pl pr => Zpart Zhat pl pr | Zpart Zhubr _ _ => zshiftr Zhubr zp | Zpart Zhat _ pr => zshiftr (zfanL pr) zp | Zpart Zhatl pl pr => Zpart (zfanR pl) pl pr | Zpart Zhatr pl pr => Zpart Zhub pl pr | Zpart Zfan0l pl pr => Zpart Zhatr pl pr | Zpart Zfan1l pl pr => Zpart Zfan0l pl pr | Zpart Zfan2l pl pr => Zpart Zfan1l pl pr | Zpart Zfan3l pl pr => Zpart Zfan2l pl pr | Zpart _ pl pr => Zpart Znil pl pr end.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(fintype path fingraph) fourcolor(hypermap geometry part quiz quiztree)