Implement MathHub Lenses

[kohlhase]

MathHub wants to be a public repository of mathematical knowledge and documents, which means everyone should be able to contribute. But it should also be a portal to high-quality material, which means some kind of quality control system. Following ideas developed for/by the Connexions Project we want to employ a system of (named) "lenses", which give a reader (preferential) access to MathHub material endorsed by a set of chosen lenses. The CNX Manual section on lenses has some more information.

At its base, a lens L is just an endorsement list, i.e. a list of MathHub knowledge items endorsed as being of sufficient quality and/or interest by L.

A MathHub reader can adopt a lens L for

• restriction: MathHub content outside L (and other lenses adopted for restriction) is invisible to this user
• preference: the MathHub front-end prefers content in L (by some mechanism to be specified for resolving preferences between lenses)

We probably want to have a way of storing lens adoptions for authenticated users.

Initially, lenses should have the following metadata:

• authors/Institution: who made this lens and feels responsible for the quality judgments in it.
• description: a description of the purpose and process of a lens.
• teaser: a short description

Probably the best way to implement a lens is as a list of MMT URIs in a GitLab file on http://gl.mathhub.info. Then we can just use GIT authentification for lens authors and GIT management/versioning features for lens content.

For the front-end process we probably want to have a separate service, which reads lenses, indexes them, and helps it by answering questions like

• given a MMT URI u to be displayed, what lenses support u (e.g. for lens badges)
• given a MMT URI u and list of adopted lenses, is u visible (restriction) and what is it's rank (preference).

Maybe this service could also take care of authentification, then the MathHub front-end only needs to keep a global variable for the user as state.

[kohlhase]

I am starting an implementation at https://github.com/MathHubInfo/

• first step is to design a JSON format for lenses, so that we can put them up on GitHub.

[kohlhase]

Instead of the GIT-based JSON file solution proposed above, we probably need a database-based back-end, which stores lenses, and a service which stores lens information; see https://github.com/MathHubInfo/lenses/issues/1

Correspondingly, the front-end needs the following extensions (probably more)

• [ ] allow the user to select/manage lenses, and some way of storing them (cookies?). I am thinking of a list of lenses which the user can tick and give relative weights. And for each list say whether it is used for restriction or preference.
• [ ] for each MMT URI page display the badges of all lenses that endorse it (possibly visualizing their relative endorsement rate), also make an interface that allows to add/delete/upvote/downvote this page in a lens. The endorsement rate of each is probably the sum of the endorsements of the respective lens weighted by the relative weight.
• [ ] for each listing of MMT URI components, restrict to the ones that have at least one restrictive lens endorsing them. Add an endorsement rate given by the back-end (and link it to an explanation) . Also add to each listing a "more items outside your lenses" item to the list.