[spothedog1]

This is what I've been thinking for the past year. Do you have any more resources where I can explore what you're talking about?

* What are some deductive reasoning engines out there?

* How are you storing the rules in a graph? Using triples?

* What query languages are you using for this?

[TrueDuality]

Sorry missed this comment. There are a surprising number of them, basically any formal solver is a deductive reasoning engine. Prolog is itself a deductive reasoning engine (and if you're going to implement a reasoning system, its probably worth going through the WAM Book over a weekend, search Google for wambook.pdf, its a publicly released book with the title "Warren's Abstract Machine: A Tutorial Reconstruction". The harder ones are inductive and abductive reasoners, which I'm not aware of any opensource ones only old papers that all do little tiny bits. A lot of deductive reasoners boil down to just depth-first-search with backtracking.

How I'm storing them is maybe interesting... Graph databases that support tagged or typed relations get you most of the way to a basic reasoning system. I'm currently storing the graph content of the knowledge base in a database called SurrealDB with the RocksDB backend (this is new to me). Learning SurrealDB has been giving me a bit of Deja Vu around building simple reasoners, there is a lot of overlap between graph theory and formal reasoning.

Rules are encoded in the program. I find it beneficial to think about this as building up lots of small tools that are aware of what they're capable of and can indicate whether they think they can make single step progress towards the goal. You might have a small tool that if you have a location and you're looking for a different location (its prerequisites for "knowing" it may be useful) you could have that tool walk your graph finding the smallest shared domain that both are a part of that can become part of the context. Building up context and learning to disambiguate things using that context is kind of the "hard part" if you want to optimize your solvers or ask complex questions.

For the Rules to be meaningful you need to have an Ontology for your database. Your Rules will be operating on top of fixed concepts, and known relation types between them. Ontologies are a BIG subject that has also faded into the mist a bit, there are some samples on http://ontologydesignpatterns.org but there are a lot of dead links on there as well. The more complex your Ontology the harder to write and/or less useful the individual tools become as they will probably have fewer opportunities to run.

Hope this helps!