// Insert the sequence as a child of `node`, but only
// if the node is not already a leaf
if (not node->is_leaf() or node == this->root_) {
- xbt_assert(!shortest_sequence.value().empty(), "A successful insertion into an interior"
- "node of a wakeup tree should never involve "
- "an empty sequence (yet here we are, with an empty sequence)");
+ // NOTE: It's entirely possible that the shortest
+ // sequence we are inserting is empty. Consider the
+ // following two cases:
+ //
+ // 1. `w` is itself empty. Evidently, insertion succeeds but nothing needs
+ // to happen
+ //
+ // 2. a leaf node in the tree already contains `w` exactly.
+ // In this case, the empty `w'` returned (viz. `shortest_seq`)
+ // such that `w [=_[E] v.w'` would be empty
this->insert_sequence_after(node, shortest_sequence.value());
}
// Since we're following the post-order traversal of the tree,
