View Compilation Error

0_0_7840595_4569.cpp: In constructor `AC_automation<low_bound, up_bound>::AC_automation(AC_trie<low_bound, up_bound>*)':
0_0_7840595_4569.cpp:87: error: `next' undeclared (first use this function)
0_0_7840595_4569.cpp:87: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_7840595_4569.cpp:87: error: `i' undeclared (first use this function)