Class: CSE 130 Subject: computer-science computer-systems Date: 2025-04-03 Teacher: **Dr. Veenstra

Chapter 1

What is a System?

• it’s a set of interconnected components that has an expected behavior observed at the interface with it’s environment.

Complexity

4 Issues of Complexity

Emergent Properties

• properties that show up only when combining individual components
• often it is used in a negative context. i.e The Millenium Bridge, London

Propagation of Effects

• problems in one component affect other components. i.e Northeast Blackout of 1965

Not proportional(incommensurate) Scaling

• not all parts of a system scale at the same rate

Tradeoffs

• what will I need to sacrifice for more of something else

4 Signs of Complexity

1. Large number of components
2. Large number of interconnections
3. Lots of irregularities
4. Long description(high information content)

Sources of Complexity

1. Interactions of requirements

• A general purpose tool that can do $X$ and other things is more complex than a special purpose tool that can only do $X$
• general purpose tool
• special purpose tool

2. Increasing efficiency, utilization, or other measure of “goodness”

• i.e. car engines
  • 1960 Chevy(simple)
    • burn gasoline, get mechanical power
  • 2015 Honda CR-V(much more complex)
    • adds: more efficient, lower emissions(better for the environment), more durable

What increase complexity

Principle of escalating complexity

• adding a requirement increases complexity out of proportion
• i.e. adding a cache requires doubling the implementation

Principle of excessive generality

• pretty self-explanatory