:: deftheorem Def20 defines @ MSAFREE:def 20 :
for S being non empty non void ManySortedSign
for X being non-empty ManySortedSet of the carrier of S
for t being Symbol of (DTConMSA X) st ex p being FinSequence st t ==> p holds
for b₄ being OperSymbol of S holds
( b₄ = @ (X,t) iff [b₄, the carrier of S] = t );