: Let {{nowrap|1=''G'' = (''V'', ''E'', ''ϕ'')}} be a graph. A circuit is a non-empty trail {{nowrap|(''e''<sub>1</sub>, ''e''<sub>2</sub>, …, ''e''<sub>''n''</sub>)}} with a vertex sequence {{nowrap|(''v''<sub>1</sub>, ''v''<sub>2</sub>, …, ''v''<sub>''n''</sub>, ''v''<sub>1</sub>)}}. | : Let {{nowrap|1=''G'' = (''V'', ''E'', ''ϕ'')}} be a graph. A circuit is a non-empty trail {{nowrap|(''e''<sub>1</sub>, ''e''<sub>2</sub>, …, ''e''<sub>''n''</sub>)}} with a vertex sequence {{nowrap|(''v''<sub>1</sub>, ''v''<sub>2</sub>, …, ''v''<sub>''n''</sub>, ''v''<sub>1</sub>)}}. |