let S be non empty non void ManySortedSign ; for V being non-empty ManySortedSet of the carrier of S
for A being MSAlgebra over S
for t being c-Term of A,V
for s being SortSymbol of S
for v being Element of V . s st t = root-tree [v,s] holds
the_sort_of t = s
let V be non-empty ManySortedSet of the carrier of S; for A being MSAlgebra over S
for t being c-Term of A,V
for s being SortSymbol of S
for v being Element of V . s st t = root-tree [v,s] holds
the_sort_of t = s
let A be MSAlgebra over S; for t being c-Term of A,V
for s being SortSymbol of S
for v being Element of V . s st t = root-tree [v,s] holds
the_sort_of t = s
let t be c-Term of A,V; for s being SortSymbol of S
for v being Element of V . s st t = root-tree [v,s] holds
the_sort_of t = s
let s be SortSymbol of S; for v being Element of V . s st t = root-tree [v,s] holds
the_sort_of t = s
let x be Element of V . s; ( t = root-tree [x,s] implies the_sort_of t = s )
x in ( the Sorts of A . s) \/ (V . s)
by XBOOLE_0:def 3;
then
x in ( the Sorts of A (\/) V) . s
by PBOOLE:def 4;
hence
( t = root-tree [x,s] implies the_sort_of t = s )
by Th14; verum