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