goalstackLib.set_backup : int -> unit

SYNOPSIS
Limits the number of proof states saved on the subgoal package backup list.

DESCRIBE
The assignable variable set_backup is initially set to 12. Its value is one less than the maximum number of proof states that may be saved on the backup list. Adding a new proof state (by, for example, a call to expand) after the maximum is reached causes the earliest proof state on the list to be discarded. For a description of the subgoal package, see set_goal.

EXAMPLE
#set_backup 0;
()  unit

#g "(HD[1;2;3] = 1) /\ (TL[1;2;3] = [2;3])";;
"(HD[1;2;3] = 1) /\ (TL[1;2;3] = [2;3])"

() : void

#e CONJ_TAC;;
OK..
2 subgoals
"TL[1;2;3] = [2;3]"

"HD[1;2;3] = 1"

() : void

#e (REWRITE_TAC[HD]);;
OK..
goal proved
|- HD[1;2;3] = 1

Previous subproof:
"TL[1;2;3] = [2;3]"

() : void

#b();;
2 subgoals
"TL[1;2;3] = [2;3]"

"HD[1;2;3] = 1"

() : void

#b();;
evaluation failed     backup:  backup list is empty

SEEALSO  b,   backup,   e,   expand,   expandf,   g,   get_state,   p,   print_state,   r,   rotate,   save_top_thm,   set_goal,   set_state,   top_goal,   top_thm

HOL  Kananaskis 0