There are compound adjectives in which each word is inflected (as adjective). When they are nominalised, should each adjective be separately nominalised or only the ultimate word?
The concrete question I have in mind is the following:
In mathematics, (mathematical objects called) topological spaces are said to be 'simply connected' under certain circumstances. What should the name of the corresponding property be? 'Simple-connectedness' or 'simply connectedness'? Should there be a hyphen in the second case? (The rules for hyphens in the adjective form are clear.)
Which is the grammatically correct usage?