1. --minimum (a,b)
2. -- inputs: a, b are real numbers.
3. --output: result: minimum (a,b)

Model of the action with an assignment statement:
1. --farmer, goat, grass, wolf = L,L.L.L.
2. Farmer, goat:= R, R
3. -farmer, goat, grass, wolf = R.R.L,L
4. --farmer: = L
5. --farmer, goat, grass, wolf = L,R,L.L
6. farmer, grass: = R, R
7. --farmer, goat, grass, wolf = R,R,R,L
8. farmer, goat: = L, L
9. --farmer, goat, grass, wolf = L,L,R,L
10. farmer, wolf: = R.R
11. --farmer, goat, grass, wolf = R,L,R,R
12. farmer: = L
13. --farmer, goat, grass, wolf = L,L,K,R
14. farmer, goat: = R,R
15. -- farmer, goat, grass, wolf = R,R,R,R

The state represented in a algorithm is set of variables. At any place the value of the variables are substituted and evaluation is done.

Let P be the required property of the inputs and Q the property of the desired outputs.
Format of specification of an algorithm:
(a) Algorithm name (Inputs)
(b) Inputs - P
(c) Outputs - Q

Let the variables a, b, c represent the glass A, glass B and Glass C respectively. Variables A, B, C can store values APPLE, GRAPE or EMPTY.
Initial State:
1.-- a, b, c : = APPLE, GRAPE, EMPTY
2. C : = b
3.-- a, b, c : = APPLE, EMPTY, GRAPE
4. b : = a
5.-- a, b, c : = EMPTY, APPLE, GRAPE
6. a : = C
7.-- a, b, c : = GRAPE, APPLE, EMPTY
Final State:
Specification:
1. Exchange ()
2. -- inputs: a, b, c :- APPLE, GRAPE, EMPTY
3.--outputs: a, b, c:- GRAPE, APPLE, EMPTY

1. hypotenuse (a, b)
2. -- inputs: a, b are real numbers, a > 0, b > 0
3 -- outputs: c²=a² + b² where c is real number, c > 0