Created
April 12, 2014 11:24
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Theorem tautology : forall P : Prop, P -> P. | |
Proof. | |
intros P H. | |
assumption. | |
Qed. | |
Theorem Modus_ponens : forall P Q : Prop, P -> (P -> Q) -> Q. | |
Proof. | |
intros. | |
apply H0. | |
apply H. | |
Qed. | |
Theorem Modus_tollens : forall P Q : Prop, ~Q /\ (P -> Q) -> ~P. | |
Proof. | |
intros. | |
destruct H. | |
intro. | |
apply H. | |
apply H0. | |
apply H1. | |
Qed. | |
Theorem Disjunctive_syllogism : forall P Q : Prop, (P \/ Q) -> ~P -> Q. | |
Proof. | |
intros. | |
destruct H. | |
destruct H0. | |
apply H. | |
apply H. | |
Qed. | |
Theorem DeMorgan1 : forall P Q : Prop, ~P \/ ~Q -> ~(P /\ Q). | |
Proof. | |
intros. | |
intro. | |
destruct H0. | |
destruct H. | |
apply H. | |
apply H0. | |
apply H. | |
apply H1. | |
Qed. | |
Theorem DeMorgan2 : forall P Q : Prop, ~P /\ ~Q -> ~(P \/ Q). | |
Proof. | |
intros. | |
intro. | |
destruct H. | |
destruct H0. | |
apply H. | |
apply H0. | |
apply H1. | |
apply H0. | |
Qed. | |
Theorem DeMorgan3 : forall P Q : Prop, ~(P \/ Q) -> ~P /\ ~Q. | |
Proof. | |
intros. | |
split. | |
intro. | |
apply H. | |
left. | |
apply H0. | |
intro. | |
apply H. | |
right. | |
apply H0. | |
Qed. | |
Theorem NotNot_LEM : forall P : Prop, ~ ~(P \/ ~P). | |
Proof. | |
intros. | |
intro. | |
apply H. | |
right. | |
intro. | |
apply H. | |
left. | |
apply H0. | |
Qed. | |
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