let S be locally_directed OrderSortedSign; :: thesis: for X being V5() ManySortedSet of
for s being Element of S holds OSFreeGen s,X = { (((OSNat_Hom (ParsedTermsOSA X),(LCongruence X)) . s) . (root-tree t)) where t is Symbol of (DTConOSA X) : ( t in Terminals (DTConOSA X) & t `2 = s ) }
let X be V5() ManySortedSet of ; :: thesis: for s being Element of S holds OSFreeGen s,X = { (((OSNat_Hom (ParsedTermsOSA X),(LCongruence X)) . s) . (root-tree t)) where t is Symbol of (DTConOSA X) : ( t in Terminals (DTConOSA X) & t `2 = s ) }
let s be Element of S; :: thesis: OSFreeGen s,X = { (((OSNat_Hom (ParsedTermsOSA X),(LCongruence X)) . s) . (root-tree t)) where t is Symbol of (DTConOSA X) : ( t in Terminals (DTConOSA X) & t `2 = s ) }
set D = DTConOSA X;
set NH = OSNat_Hom (ParsedTermsOSA X),(LCongruence X);
set A = { (((OSNat_Hom (ParsedTermsOSA X),(LCongruence X)) . s) . (root-tree t)) where t is Symbol of (DTConOSA X) : ( t in Terminals (DTConOSA X) & t `2 = s ) } ;
thus OSFreeGen s,X c= { (((OSNat_Hom (ParsedTermsOSA X),(LCongruence X)) . s) . (root-tree t)) where t is Symbol of (DTConOSA X) : ( t in Terminals (DTConOSA X) & t `2 = s ) } :: according to XBOOLE_0:def 10 :: thesis: { (((OSNat_Hom (ParsedTermsOSA X),(LCongruence X)) . s) . (root-tree t)) where t is Symbol of (DTConOSA X) : ( t in Terminals (DTConOSA X) & t `2 = s ) } c= OSFreeGen s,X

proof

let x be set ; :: according to TARSKI:def 3 :: thesis: ( not x in OSFreeGen s,X or x in { (((OSNat_Hom (ParsedTermsOSA X),(LCongruence X)) . s) . (root-tree t)) where t is Symbol of (DTConOSA X) : ( t in Terminals (DTConOSA X) & t `2 = s ) } )
assume x in OSFreeGen s,X ; :: thesis: x in { (((OSNat_Hom (ParsedTermsOSA X),(LCongruence X)) . s) . (root-tree t)) where t is Symbol of (DTConOSA X) : ( t in Terminals (DTConOSA X) & t `2 = s ) }
then consider a being set such that
A1: ( a in X . s & x = ((OSNat_Hom (ParsedTermsOSA X),(LCongruence X)) . s) . (root-tree [a,s]) ) by Def26;
A2: [a,s] in Terminals (DTConOSA X) by A1, Th4;
then reconsider t = [a,s] as Symbol of (DTConOSA X) ;
t `2 = s by MCART_1:7;
hence x in { (((OSNat_Hom (ParsedTermsOSA X),(LCongruence X)) . s) . (root-tree t)) where t is Symbol of (DTConOSA X) : ( t in Terminals (DTConOSA X) & t `2 = s ) } by A1, A2; :: thesis: verum

end;

let x be set ; :: according to TARSKI:def 3 :: thesis: ( not x in { (((OSNat_Hom (ParsedTermsOSA X),(LCongruence X)) . s) . (root-tree t)) where t is Symbol of (DTConOSA X) : ( t in Terminals (DTConOSA X) & t `2 = s ) } or x in OSFreeGen s,X )
assume x in { (((OSNat_Hom (ParsedTermsOSA X),(LCongruence X)) . s) . (root-tree t)) where t is Symbol of (DTConOSA X) : ( t in Terminals (DTConOSA X) & t `2 = s ) } ; :: thesis: x in OSFreeGen s,X
then consider t being Symbol of (DTConOSA X) such that
A3: ( x = ((OSNat_Hom (ParsedTermsOSA X),(LCongruence X)) . s) . (root-tree t) & t in Terminals (DTConOSA X) & t `2 = s ) ;
consider s1 being Element of S, a being set such that
A4: ( a in X . s1 & t = [a,s1] ) by A3, Th4;
s = s1 by A3, A4, MCART_1:7;
hence x in OSFreeGen s,X by A3, A4, Def26; :: thesis: verum