---
type: "Research"
title: "Kairouz et al. — Advances and open problems (2019)"
description: "The field's open problems: heterogeneity, privacy, fairness, evaluation."
resource: "https://arxiv.org/abs/1912.04977"
tags: [fl, survey, research]
generated: { by: human:crpage, at: 2026-07-09T09:44:00Z }
status: stable
sources: [{ id: primary, resource: "https://arxiv.org/abs/1912.04977" }]
---

Formalised FL's open problems — systems heterogeneity, privacy, fairness, personalisation, compression, communication efficiency, robustness and **evaluation** — the standard reference map of the field.

Relates to: [Non-IID data](../federated/non-iid-data.md), [Federated evaluation](../federated/federated-evaluation.md).