The parallel processing option is OR logic; take all available Paths at the same time.
Technically, we are exchanging SPACE in the form of multiple concurrent processors for TIME in the form of sequential steps and Backtracking.
The XOR logic of one-or-the-other, in both concept and process, reduces or at least delays Complexity.
The OR logic of one-and-both maintains ambiguity, which has been inappropriately interpreted as failure to make a Decision.
~
Bricken, Iconic Arithmetic Volume III: The Structure of Imaginary And Infinite Forms, pdf 
, p. 205.
DOT FROM lambda-browsing