:like nailing jelly to a tree: adj. Used to describe a task thought
to be impossible, esp. one in which the difficulty arises from
poor specification or inherent slipperiness in the problem domain.
"Trying to display the `prettiest' arrangement of nodes and arcs
that diagrams a given graph is like nailing jelly to a tree,
because nobody's sure what `prettiest' means algorithmically."
-- The AI Hackers Dictionary
orthogonal: [from mathematics] adj. Mutually independe well
separated; sometimes, irrelevant to. Used in a generalization of
its mathematical meaning to describe sets of primitives or
capabilities that, like a vector basis in geometry, span the
entire `capability space' of the system and are in some sense
non-overlapping or mutually independent....