do we need an h-feed authorship algorithm?

how should we determine an h-feed's author? we [discussed on #indieweb-dev](https://chat.indieweb.org/dev/2020-04-06#t1586209892016000) and [on #microformats](https://chat.indieweb.org/microformats/2020-04-07#t1586234113620600), and the short answer is evidently that we don't know yet. we don't yet have an "authoritative" way, at least for h-feeds without an explicit `p-author` property. [representative h-card](https://indieweb.org/representative_h-card) and [authorship algorithm](https://indieweb.org/authorship-spec) are both related, but neither is the exact answer. the [authorship wiki page has an _Authorship for streams of posts_ section](https://indieweb.org/authorship#Authorship_for_streams_of_posts) that's close, but thin.

so, do we need a new h-feed authorship algorithm? or should we extend one of those two algorithms? or something else?

@tantek [said here](https://chat.indieweb.org/dev/2020-04-07#t1586266635329200) that we still need to do some research and come up with an algorithm. we don't necessarily have the "right" one just yet. so, i've filed this as a place to track research. feel free to close this and move it to the wiki instead if you prefer!

> snarfed, h-feed authorship is an interesting problem and worth researching & brainstorming properly rather than seeing if h-entry approaches “just work” because that may be overdoing it
> Better to collect examples (links, analysis) of h-feed elements that you’re trying to parse and analyze them to figure out a minimum algorithm based on examples
> The “XML approach” would be to assume / require authors/publishers always use an author property and then “just” look for that. While a good starting point, it’s obviously a bad approach to optimize for developer convenience rather than researching reasonable real world examples and making sure to handle them
> It’s also a bad approach to “just try” some other similar algorithm to see if it “just works” as you’re likely making all sorts of bad assumptions by doing so
> So I disagree with both “just use representative h-card” and “just use h-entry authorship but for h-feed”
> There’s no shortcut here. If you want a good algorithm it has to start with documenting & analyzing real world publishing examples

(this was motivated by @alexmingoia's recent [granary#195](https://github.com/snarfed/granary/issues/195) issue that granary doesn't determine an h-feed's author very well right now. it naively uses [authorship algorithm](https://indieweb.org/authorship-spec), which is designed for h-entry, not h-feed.)

cc @kevinmarks @aaronpk. originally filed as microformats/microformats2-parsing#49.

Start with the authorship wiki’s “Authorship for streams of posts” section, the representative h-card and authorship algorithm pages, and granary#195 for context. Collect and analyze real-world h-feed examples, then determine whether a new algorithm or an extension is needed. Done means documenting a researched, agreed approach for feeds without explicit p-author.

Written by the indexing model from the issue text.