There are two important cases : ( i ) a simple closed chain and ( ii ) a simple open chain . There are two important special cases : ( i ) a simple closed chain , and ( ii ) a simple open chain .
Terdapat dua kes penting: (i) satu rantai tertutup mudah dan (ii) satu rantai terbuka mudah. Terdapat dua kes khas penting: (i) rantai tertutup mudah, dan (ii) rantai terbuka mudah.