hegg
asami
hegg | asami | |
---|---|---|
3 | 6 | |
72 | 626 | |
- | 0.0% | |
6.7 | 0.0 | |
15 days ago | about 2 years ago | |
Haskell | Clojure | |
BSD 3-clause "New" or "Revised" License | Eclipse Public License 1.0 |
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hegg
- [ANN] E-graphs and equality saturation: hegg 0.1
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Ask HN: What are some 'cool' but obscure data structures you know about?
Equality graphs (e-graphs) for theorem proving and equality saturation and other equality-related things.
They're awesome data structures that efficiently maintain a congruence relation over many expressions
> At a high level, e-graphs extend union-find to compactly represent equivalence classes of expressions while maintaining a key invariant: the equivalence relation is closed under congruence.
e.g. If I were to represent "f(x)" and "f(y)" in the e-graph, and then said "x == y" (merged "x" and "y" in the e-graph), then the e-graph, by congruence, would be able to tell me that "f(x) == f(y)"
e.g. If I were to represent "a(2/2)", in the e-graph, then say "2/2 == 1", and "x1 == x", by congruence the e-graph would know "a*(2/2) == a" !
The most recent description of e-graphs with an added insight on implementation is https://arxiv.org/pdf/2004.03082.pdf to the best of my knowledge.
P.S: I'm currently implementing them in Haskell https://github.com/alt-romes/hegg
asami
- Ask HN: What are some 'cool' but obscure data structures you know about?
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Ask HN: Why are relational DBs are the standard instead of graph-based DBs?
Unlike some other commenters, I agree that graph models are usually a better fit for most data than relational models. There's been some interesting work in recent years developing this idea: in the Clojure world there's Datomic, XTDB, and a host of competitors, all of which build on work from Semantic Web/SPARQL/triplestores and logic programming. Some are even intended to be used as primary datastores: they support some amount of schema and constraints, have well-defined consistency and ACID guarantees, etc. This makes them unlike graph databases like Neo4J and others, which fill an architectural role more like Elasticsearch as a read-optimization tool. Here's an interesting talk making a case for triple-based databases.
- Introduction to the Asami Graph Database
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How to query Datomic, Datascript, Asami, or other graph databases
Despite the documentation that exists, I've heard many people who have been confused about how to query Datomic, Datascript, Asami, or other graph databases. So I've made an attempt at explaining it https://github.com/threatgrid/asami/wiki/Introduction
- Introduction (To Graph Databases)
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Asami
The first Graph implementation for Asami was a simple in-memory data structure, described in my ClojureD talk. The code for this appears in asami.index. This file started much smaller (as referenced above), but has since expanded with the needs extended functionality, such as transactions, and transitive closure operations.
What are some alternatives?
Folly - An open-source C++ library developed and used at Facebook.
datascript - Immutable database and Datalog query engine for Clojure, ClojureScript and JS
us - An alternative interface to Sia
crux - General purpose bitemporal database for SQL, Datalog & graph queries. Backed by @juxt [Moved to: https://github.com/xtdb/xtdb]
RoaringBitmap - A better compressed bitset in Java: used by Apache Spark, Netflix Atlas, Apache Pinot, Tablesaw, and many others
datahike - A durable Datalog implementation adaptable for distribution.
CPython - The Python programming language
datalevin - A simple, fast and versatile Datalog database
ann-benchmarks - Benchmarks of approximate nearest neighbor libraries in Python
Apache AGE - Graph database optimized for fast analysis and real-time data processing. It is provided as an extension to PostgreSQL. [Moved to: https://github.com/apache/age]
multiversion-concurrency-contro
naga - Datalog based rules engine