Exercises
[21Z]Let \(X_ 1,X_ 2\) be two disjoint and well-ordered sets. Let \(W\) be the concatenation of \(X_ 1\) with \(X_ 2\): show that it is well ordered.
[21Z]Let \(X_ 1,X_ 2\) be two disjoint and well-ordered sets. Let \(W\) be the concatenation of \(X_ 1\) with \(X_ 2\): show that it is well ordered.