#graphdata — Public Fediverse posts

I am thinking about an interesting problem right now.

Suppose I have a DAG of objects. Every object contains three data points:

* A list of parents (via Content-address hashes)
* A pointer to some content (almost irrelevant for this thought process)
* A version number (irrelevant for this thought process)

I have a limited but unknown number of peers that are allowed to "post" to that DAG. Once a peer discovers that another node has posted to the DAG, they either fast-foward or merge (which is trivial here) and go on.
All peers gossip all the time, so fast-forwarding is expected to be the "normal case" when all peers are online - but in case of network split there is no issue.

Now, suppose I want to allow "rewriting" the DAG.
That means, one node decides that deep down in the DAG, they want to change a node. That would change all other nodes that come after it.

How would the other peers know that the node was rewritten?

Two ideas:

* All peers keep track of "this other peer points to this hash right now". Once a peer rewrites their DAG, other peers can see that rather easily. That would involve some tricky logic, but I guess would be possible 🤔 The other peers can then update their stuff to that new DAG (and if needed even "rebase" changes that they have done between the rewrite and now, if there was a network split during that time)
* The second option would involve adding timestamps to the DAG nodes, so other nodes can see that a portion of the DAG was rewritten

The second option would add more fields to the DAG nodes, which I would like to not do, because they should be as light as possible.

What do you think? :boost_ok:

#algorithms #softwaredevelopment #dag #distributedsystems #graphdata #datatypes

Rules Of River Avulsion Change Downstream
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https://doi.org/10.1038/s41586-024-07964-2 <-- shared paper
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#GIS #spatial #mapping #river #water #hydrology #avulsion #geomorphology #geomorphometry #floodplain #flood #flooding #course #risk #hazard #elevation #topography #hydromorphic #hydrospatial #model #modeling #factors #coast #coastal #mountain #fan #riskassessment #global #spatialanalysis #management #mitigation #prediction #remotesensing #ICESat2 #FABDEM #Copernicus #algorithm #fluvial #alluvial #sediment #alluvium #sediment #machinelearning #graphdata #geostatistics #spatiotemporal

Quite happy with how my little side-project has turned out so far.

It started off as an itch I wanted to scratch about named entity recognition, took me through #lstm to #transformer to #graphdata etc. Been a lot of fun and I've learnt a lot.

https://syracuse.1145.am