Extensions of Relational Codd’s Algebra and DB Category - Big Data Integration Theory - page 221

binary nodes such that both of its arguments are the terms without another binary
nodes are denominated atomic nodes (in Example 33 the binary nodes denoted by
↓ 2 , 3 , 7 are atomic).

Based on this consideration, we present the following algorithm for the reduction
of a (tree) term t RA ∈ T RA X into an equivalent path-term with the unique leaf t RA ∈
T RA X :
1. If t RA is a tree-term (with binary nodes), then go to Step 2. If this path-term
contains the unary operations _

n , n =

a,name,e go to Step 3; otherwise go to Step 4.