4.6.2 Method for Writing With such that
In addition, there is another way of writing as follow:
for x,y st P[x,y] holds Q[x,y]
proof
let xs,y such that L:P[x,y];
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thus Q[x,y];
end;
Further, labels are usually entered after such that; however, in this example (this case L) they are not necessary. The first line is st and the third line is such that.