Tomorrow's lunch
This is tomorrow's ESSLLI lunchmenu:
- Starters
- green salad
melon
tomato salad
rabbit pate - Main dishes
- rock salmon with mayonnaise and capers
roast beef with girolle mushroom sauce
pasta, courgette and cheese bake - Desert
- cheese
yoghurt
Paris Brest pastry
Use the predicates starter/1, main/1,
and desert/1 to represent tomorrow's options in
Prolog.
Solution
If you are very hungry, you can have one starter, one main dish, and one desert. If you are not so hungry (or have a course right after lunch), you might want to only have a starter and a main dish or a desert and a main dish. If you are currently on a diet, it's probably wisest to only take a starter.
Define a predicate menu/4 which finds menus for you
depending on whether you are hungry, not so hungry or on a
diet. So, menu(Status,X,Y,Z) should be true if
Status is hungry and X,
Y, Z are a starter, a main dish, and a
desert, respectively. It should also be true if
Status is not_so_hungry, and either
X is a starter, Y a main dish, and
Z is nothing, or X is
nothing, Y is a main dish, and
Z is a desert. Finally,
menu(Status,X,Y,Z) should be true if
Status is on_diet, X is a
starter and Y and Z are
nothing.
Hint