let n be non empty Nat; :: thesis: for S being non empty non void n PC-correct PCLangSignature

for L being language MSAlgebra over S

for F being PC-theory of L

for A being Formula of L holds (\not (\not A)) \imp A in F

let S be non empty non void n PC-correct PCLangSignature ; :: thesis: for L being language MSAlgebra over S

for F being PC-theory of L

for A being Formula of L holds (\not (\not A)) \imp A in F

let L be language MSAlgebra over S; :: thesis: for F being PC-theory of L

for A being Formula of L holds (\not (\not A)) \imp A in F

let F be PC-theory of L; :: thesis: for A being Formula of L holds (\not (\not A)) \imp A in F

let A be Formula of L; :: thesis: (\not (\not A)) \imp A in F

( ((\not A) \imp (\not (\not (\not A)))) \imp ((\not (\not A)) \imp A) in F & (\not A) \imp (\not (\not (\not A))) in F ) by Def38, Th64;

hence (\not (\not A)) \imp A in F by Def38; :: thesis: verum

for L being language MSAlgebra over S

for F being PC-theory of L

for A being Formula of L holds (\not (\not A)) \imp A in F

let S be non empty non void n PC-correct PCLangSignature ; :: thesis: for L being language MSAlgebra over S

for F being PC-theory of L

for A being Formula of L holds (\not (\not A)) \imp A in F

let L be language MSAlgebra over S; :: thesis: for F being PC-theory of L

for A being Formula of L holds (\not (\not A)) \imp A in F

let F be PC-theory of L; :: thesis: for A being Formula of L holds (\not (\not A)) \imp A in F

let A be Formula of L; :: thesis: (\not (\not A)) \imp A in F

( ((\not A) \imp (\not (\not (\not A)))) \imp ((\not (\not A)) \imp A) in F & (\not A) \imp (\not (\not (\not A))) in F ) by Def38, Th64;

hence (\not (\not A)) \imp A in F by Def38; :: thesis: verum