The Twelve Threads
Twelve patterns run through all seven layers. They are introduced
fully in Chapter 3. Here they are by name, to give you a first
orientation:
- T1 Hashing — Modular arithmetic; mapping large
spaces to small ones
- T2 Trees — Hierarchical ordering; fast lookup via
sorted structure
- T3 Graphs — Relationships as first-class objects;
traversal
- T4 Queues — Ordered processing; decoupling producer
from consumer
- T5 Caching — Trade memory for speed; avoid
recomputing known results
- T6 Redundancy — Copies protect against loss;
replication enables scale
- T7 State Machines — Systems that remember;
transitions between defined states
- T8 Divide & Conquer — Split the problem; solve
the parts; combine results
- T9 Consensus — Agreement in the presence of
disagreement or failure
- T10 Encoding — Representing information; choosing
the right representation
- T11 Feedback Loops — Systems that react to their
own output
- T12 Tradeoffs — Every decision is an optimisation
under constraints
These threads are the vertical axis of the series. Every chapter in
every book activates one or more of them. When you read a chapter and
see “T5” in the thread reference, you can trace that thread backwards to
its mathematical root and forward to its product manifestation.