# Set CRDT com M\'ultiplas Pol\'iticas de Resolu\c{c}\~ao de Conflitos

## TL;DR

This paper introduces a novel CRDT set design that allows multiple conflict resolution policies to be applied dynamically, enabling more flexible conflict management in replicated data systems.

## Contribution

It presents a new CRDT set implementation that supports multiple conflict resolution policies, allowing applications to override default semantics for specific operations.

## Key findings

- The proposed CRDT set supports multiple conflict policies.
- It enables overriding default add-wins semantics for specific removes.
- The design is evaluated and shown to be effective.

## Abstract

Um CRDT \'e um tipo de dados que pode ser replicado e modificado concorrentemente sem coordena\c{c}\~ao, garantindo-se a converg\^encia das r\'eplicas atrav\'es da resolu\c{c}\~ao autom\'atica de conflitos. Cada CRDT implementa uma pol\'itica espec\'ifica para resolver conflitos. Por exemplo, um conjunto CRDT add-wins d\'a prioridade ao "add" aquando da execu\c{c}\~ao concorrente de um "add" e "rem" do mesmo elemento. Em algumas aplica\c{c}\~oes pode ser necess\'ario usar diferentes pol\'iticas para diferentes execu\c{c}\~oes de uma opera\c{c}\~ao -- por exemplo, uma aplica\c{c}\~ao que utilize um conjunto CRDT add-wins pode querer que alguns "removes" ganhem sobre "adds" concorrentes. Neste artigo \'e apresentado e avaliado o desenho dum conjunto CRDT que implementa as sem\^anticas referidas. --- Conflict-Free Replicated Data Types (CRDTs) allow objects to be replicated and concurrently modified without coordination. CRDTs solve conflicts automatically and provide eventual consistency. Typically each CRDT uses a specific policy for solving conflicts. For example, in an add-wins set CRDT, when an element is concurrently add and removed in different replicas, priority is given to add, i.e., the element stays in the set. Unfortunately, this may be inadequate for some applications - it may be desired to overrule the default policy for some operation executions. For example, an application using an add-wins set may want some removes to win over concurrent adds. This paper present the design of a set CRDT that implements such semantics.