I use the following conventions in the references :

- PDA = Programming: The Derivation of Algorithms

*Programming Exercises, via Kaldewaij*

- The number of array element pairs whose product is positive
- All array elements positive?
- The maximum element
- The maximum pair difference
- The maximum squared difference
- The maximum non-empty segment sum
- The existence of the true-false pivot
- Maximal credit
- The maximum segment product
- Multiplication
- The exponent of 3 in the prime factorisation of N
- Base X to decimal conversion
- fusc
- At least one zero element
- The existence of a particular subsequence