Abstract Predecessor Tree is Composed of Unique Infinite Subsets of Odd Integers

-- a) by construction: successive subdivision of root node set
       -- all sets at any level are disjoint
       -- all sets in l.d.a.s are disjoint
       -- sets in separate branches of the tree are disjoint
       -- leaf sets "on the way down during formula development" are subsets of their parents but become disjoint "on the way back up"

-- b) by examination of characterizing formulas
       -- Two subsets, defined by d*n+c and d'*n+c' are disjoint iff c and c' are not congruent mod gcd(d,d').
       -- proof is again due to Margaret Maxfield

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