2.3 Vertical Thinking
2.3.1 Tennis Example
2.3.1.1 Solution
2.3.1.2 Comment
2.3.2 Definition
2.3.2.1 Highway Illustration
2.3.2.2 Digging Holes
2.3.3 Logic
2.3.3.1 Experts
2.3.3.2 Boundaries
2.3.4 Consequences
2.3.5 Criticisms