Assertion: sub tree | /r/HasProperty | empty
Facets:
Source sentences:
text: if T 1 and T 2 are extended binary trees, then denote by T 1 • T 2 the extended binary tree obtained by adding a root r connected to the left to T 1 and to the right to T 2 [ clarification needed where did the 'r' go in the 'T 1 • T 2 ' symbol] by adding edges when these sub-trees are non-empty.