---
title: "Deep Dive: Cardinalities"
url: "https://docs.noreja.com/en/article/deep-dive-cardinalities"
language: "en"
last_updated: "2026-02-23T07:37:59.795Z"
---

# Deep Dive: Cardinalities

Cardinalities in process graphs provide critical structural insight into how activities relate to one another across case instances. They describe the multiplicity of transitions between activities—whether flows are strictly linear, branching, merging, optional, or iterative. By interpreting cardinality patterns such as 1:1, 1:n, or n:m, analysts can detect split-merge behavior, identify looping structures, uncover optional paths, and better understand structural complexity within business processes. This makes cardinality analysis an essential tool for diagnosing process design, performance dynamics, and exceptional execution patterns.

## Understanding Cardinalities in Process Graphs

Cardinalities in process graphs help you understand the structural relationship between different activities across case instances. They describe **how many times** an activity transitions to another activity – in other words, whether it’s a **one-to-one**, **one-to-many**, or **many-to-many** relationship.

This concept is essential when analyzing recurring behaviors, split-merge patterns, or exceptional flows in business processes.

## What does a Cardinality represent?

Each arrow in the process graph can include a cardinality label like `1:1`, `1:n`, or `0…1:1`, describing the **minimum and maximum amount of connections** between two activity types, across all case instances.

The format is always:

`[Source multiplicity] : [Target multiplicity]` 

## Common Types of Cardinalities

Here’s a breakdown of the most common patterns:

### **1:1 – One-to-One**

Each instance of the source activity is followed by **exactly one** target activity, and vice versa.

**Interpretation:** This path is executed **once per case** and shows a strong linearity.

![1:1 – One-to-One](https://cdn-assets.productfruits.com/c69d9233-82bf-4673-acc6-b7dc05298301)

Example: `Schaden anlegen → Schaden einpflegen`  
`1:1` means each created claim has exactly one follow-up step.

* * *

### **1:n – One-to-Many**

One source activity leads to **multiple** instances of the next activity.

**Interpretation:** A single event triggers **several follow-up actions**.

![1:n – One-to-Many](https://cdn-assets.productfruits.com/ca029dc1-895a-404b-91a9-ce8b5134a10f)

Example: `dbo.TypeC → dbo.TypeE`  
Cardinality like `1:0…3` means: one `TypeC` event can lead to up to 3 `TypeE` events.

* * *

### **n:1 – Many-to-One**

Multiple source activities lead to **the same** target activity.

**Interpretation:** A consolidation point – different branches **merge** into one step.

![](https://cdn-assets.productfruits.com/ba510809-0b94-4e25-b0d9-65a626b605cd)

Example: `dbo.TypeB → dbo.TypeC` with `1…2:0…1`  
This means: multiple `TypeB` events can lead into one `TypeC`.

* * *

### **n:m – Many-to-Many**

Multiple events on both sides interact with each other.

**Interpretation:** A **looping or repeating structure**, such as rework or batch processing.

![n:m – One-to-Many](https://cdn-assets.productfruits.com/2929d850-1da1-4bb6-ae82-5c3056f26e26)

Example: You’ll see values like `1…2:0…2`, meaning each side has multiple mappings – often seen in complex service processes or when “retries” occur.

* * *

### **0:1 / Optional Flows**

A `0` indicates that the transition **might not always occur**.

![0:1 / Optional Flows](https://cdn-assets.productfruits.com/59ebbd6c-3686-4698-97eb-75459c2013dc)

Example: `dbo.TypeE → dbo.TypeF` with `0…1:0…1`  
Some cases skip this step entirely.

* * *

## Practical Use Cases

Identify **splits** in process logic (e.g. invoice → multiple dunning steps)

Spot **merges** from parallel processing (e.g. approvals → finalization)

Detect **optional** paths and edge cases

Evaluate **looping behavior** in service or rework processes

Optimize **resource planning** by understanding bursty or linear transitions