# SE2 - lesson 03
#### Elisabeta di Nitto
##### 14 October 2015
## Requirement Engineering

#### Late error correction is costly
According to an EU survey,  
Problems in software development are divided into:
- \> 50% requirement specification
- 50% requirement management

#### What makes RE so complex?

- __Multiple concerns__
    - functional, quality, development
    - hard and soft concerns
- __Multiple stakeholders__ with different backgrounds
    - clients
    - users
    - domain experts
    - developers

#### What do requirements engineers do?

- Eliciting information
- Modelling and analisys
- Communicating requirements
- Negotiating and agreeing requirements
- Managing and evolving requirements

### The world and the machine

- The __machine__: the portion of system to be developed
- The __world__: Portion of the real world affected by the machine  

The *purpose* of the machine is always in the world

#### World phenomena