:: deftheorem Def34 defines P#0 FOMODEL4:def 34 :
for S being Language
for b₂ being Relation of (bool (S -sequents)),(S -sequents) holds
( b₂ = P#0 S iff for Seqts being Element of bool (S -sequents)
for seqt being Element of S -sequents holds
( [Seqts,seqt] in b₂ iff seqt Rule0 Seqts ) );