Sincere thanks for taking the trouble to contribute to a potential definition of "dead". I'm hoping to develop further my understanding of the mental models that people construct and it's a reasonably reliable phenomenon that definitions nearly always raise interesting and useful questions, the answers to which often shed light on the underlying assumptions and semantic associations.
From your post, I receive confirmation of my otherwise tentative conclusion that a characterisation of exchanges is required; any old exchange won't necessarily be acceptable so clearly there are further details to be elicited.
Pretty much the same goes for "attention" and "support"; both are quite widely-used terms but there is no corresponding widely-agreed consensus of what they actually mean (at least in terms of motivating the generation of an answer specific to pNut).
Thanks to your post, I'm now prompted to go away and consider "attention from whom" and "what kind of attention". Generating useful definitions of "support" and "dev" that will be comprehensible to the technically uninformed presents a tough challenge and neither have a trivial solution.
As for "value", I'm going to treat that as a user-supplied function for which the parameters and contextual attributes are beyond characterisation.
Thanks again.
Cheers
Graham