# A framework for establishing Strong Eventual Consistency for Conflict-free Replicated Datatypes

 Title: A framework for establishing Strong Eventual Consistency for Conflict-free Replicated Datatypes Authors: Victor B. F. Gomes (vb358 /at/ cl /dot/ cam /dot/ ac /dot/ uk), Martin Kleppmann (mk428 /at/ cl /dot/ cam /dot/ ac /dot/ uk), Dominic P. Mulligan (Dominic /dot/ Mulligan /at/ arm /dot/ com) and Alastair R. Beresford (arb33 /at/ cl /dot/ cam /dot/ ac /dot/ uk) Submission date: 2017-07-07 Abstract: In this work, we focus on the correctness of Conflict-free Replicated Data Types (CRDTs), a class of algorithm that provides strong eventual consistency guarantees for replicated data. We develop a modular and reusable framework for verifying the correctness of CRDT algorithms. We avoid correctness issues that have dogged previous mechanised proofs in this area by including a network model in our formalisation, and proving that our theorems hold in all possible network behaviours. Our axiomatic network model is a standard abstraction that accurately reflects the behaviour of real-world computer networks. Moreover, we identify an abstract convergence theorem, a property of order relations, which provides a formal definition of strong eventual consistency. We then obtain the first machine-checked correctness theorems for three concrete CRDTs: the Replicated Growable Array, the Observed-Remove Set, and an Increment-Decrement Counter. BibTeX: @article{CRDT-AFP, author = {Victor B. F. Gomes and Martin Kleppmann and Dominic P. Mulligan and Alastair R. Beresford}, title = {A framework for establishing Strong Eventual Consistency for Conflict-free Replicated Datatypes}, journal = {Archive of Formal Proofs}, month = jul, year = 2017, note = {\url{http://isa-afp.org/entries/CRDT.html}, Formal proof development}, ISSN = {2150-914x}, } License: BSD License Used by: IMAP-CRDT