;;; Dribble file "proof1" started
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Step 1 [1]
 
?- (l (p v (~ p)))
 
SYSTEM T>> l-right 
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Step 2 [1]
 
?- (p v (~ p))
 
SYSTEM T>> indirect-proof 
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Step 3 [1] 
 
?- false
 
1. (~ (p v (~ p)))

SYSTEM T>> rewrite ~<pvq>==>~p&~q 1 
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Step 4 [1] 
 
?- false
 
1. ((~ p) & (~ (~ p)))

SYSTEM T>> &-left 
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Step 5 [1] 
 
?- false
 
1. (~ p)
2. (~ (~ p))

SYSTEM T>> contradiction 
;;; Dribble file "proof1" finished
