Let x0 of type ο be given.
Let x1 of type ο be given.
Apply xm with
x0,
or (not x0) (not x1) leaving 2 subgoals.
Assume H1: x0.
Apply xm with
x1,
or (not x0) (not x1) leaving 2 subgoals.
Assume H2: x1.
Apply H0 with
or (not x0) (not x1).
Apply andI with
x0,
x1 leaving 2 subgoals.
The subproof is completed by applying H1.
The subproof is completed by applying H2.
Apply orIR with
not x0,
not x1.
The subproof is completed by applying H2.
Apply orIL with
not x0,
not x1.
The subproof is completed by applying H1.