> ## Documentation Index
> Fetch the complete documentation index at: https://doc.lucidworks.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Fusion AI 4.0.0 Release Notes

[localhost link]: http://localhost:3000/docs/4/fusion-ai/release-notes/4.0.0-release-notes

[mintlify link]: https://doc.lucidworks.com/docs/4/fusion-ai/release-notes/4.0.0-release-notes

[old doc.lw link]: https://doc.lucidworks.com/fusion-ai/4.2/442

**Release date:** 21 February 2018

Fusion AI is a license-controlled subset of Fusion features. Starting with Fusion 4.0, a Fusion Server license enables the basic Fusion feature set, while a Fusion AI license enables these additional features:

* Signals
* App Insights (new in 4.0)
* Smart jobs

  * ALS Recommender Jobs
  * Bisecting KMeans Clustering Jobs
  * Cluster Labeling Jobs
  * Co-Occurrence Similarity Jobs
  * Collection Analysis Jobs
  * Document Clustering Jobs
  * Ground Truth Jobs
  * Head/Tail Analysis Jobs (new in 4.0)
  * Item Similarity Recommender Jobs
  * Levenshtein Spell Checking Jobs
  * Logistic Regression Classifier Training Jobs
  * Matrix Decomposition-Based Query-Query Similarity Jobs
  * Outlier Detection Jobs
  * Random Forest Classifier Training Jobs
  * Ranking Metrics Jobs
  * SQL-Based Experiment Metric Jobs
  * Statistically Interesting Phrases Jobs
  * Token and Phrase Spell Correction Jobs (new in 4.0)
* REST APIs

  * Experiments API
  * Recommendations API
  * Signals Aggregator API
  * Signals API
* Index pipeline stages

  * Machine Learning index stage
  * OpenNLP NER Extractor index stage
  * Signal Formatter index stage
  * Update Experiment index stage
* Query pipeline stages

  * Advanced Boosting query stage
  * Analytics Catalog query stage
  * Experiment query stage
  * Machine Learning query stage
  * More Like This query stage
  * Recommend Items for Item query stage
  * Recommend Items for User query stage
  * Recommendation Boosting query stage

## New features

* **App Insights**\
  [App Insights](/docs/4/fusion-ai/concepts/insights/overview) provides detailed, real-time, searchable reports and visualizations derived from your [signals data](/docs/4/fusion-ai/concepts/signals-and-aggregations/signals/overview). It also provides alerts and triggers to notify you when specific events occur.

  <Note>
    Pre-4.0 signals data will not produce useful visualization in App Insights. New signals generated with Fusion 4.0 will produce the best results.
  </Note>

* **New jobs**

  * [Head/Tail Analysis](/docs/4/fusion-ai/reference/jobs/head-tail-analysis)

    Perform head/tail analysis of queries from collections of raw or aggregated signals, to identify underperforming queries and the reasons. This information is valuable for configuring better synonyms, auto-suggest, recommendations, and so on, in order to improve conversion rates.
  * [Token and Phrase Spell Correction](/docs/4/fusion-ai/reference/jobs/token-and-phrase-spell-correction)

    Extract tail tokens (one word) and phrases (two words) and find similarly-spelled head tokens and phrases. If several matching heads are found for each tail, the job can compare and pick the best correction using multiple configurable criteria.

## Improvements

* **Experiment management features**
  The Fusion UI now includes interfaces for running and managing [experiments](/docs/4/fusion-ai/concepts/experiments/overview).

* **SQL for aggregations**
  By default, [aggregation jobs are now defined using Spark SQL](/docs/4/fusion-ai/concepts/signals-and-aggregations/aggregations/sql-aggregations). To use the old aggregation configuration scheme in the Fusion UI, click **Advanced** in the Aggregation job configuration panel.

## Other changes

* **Bisecting Kmeans Clustering Jobs are now called [Document Clustering Jobs](/docs/4/fusion-ai/reference/jobs/document-clustering)**

* **The data structure for signals has changed**
  See [Signals](/docs/4/fusion-ai/concepts/signals-and-aggregations/signals/overview) for complete details about the new structure.

* **The Experiments API is no longer experimental**
  The [API](/docs/4/fusion-ai/reference/api/experiments-api) and other [experiments](/docs/4/fusion-ai/concepts/experiments/overview) features are now fully functional.

* **Aggregator API is deprecated**
  The `/aggregator` endpoints are deprecated in this release. Aggregations are now managed through the `/spark` endpoints.