Answers to CS5031 Exercises 1: ECO

1.

a)

CARNIVP lion, tiger, cat, man, dog;
VEGET minnow, man, dog;
lion EATS man WITH dog;
lion WITH tiger EATS man;	action /= rest op identifier
minnow IS EATEN BY cat  	missing ;

b)

VEGETABLE onions, leeks;
VEGET Fred, Albert;
Fred HATES onions WITH leeks;
BEGIN Fred EATS onions; Albert EATS leeks; END	missing ;
CARNIV lion; Albert IS EATEN BY lion AND lion EATS onions; onions IS EATEN BY
Fred WITH leeks;

c)

MALE Jack; FEMALE Joy; CARNIV Joy;
Jack LOVES Joy; Joy HATES Jack;
Jack IS EATEN BY Joy; lion EATS Jack WITH Joy;
lion LOVES Jack with Joy;
Jack AND Joy HATES lion;	AND must link actions, not identifiers

2. What are the semantics of a syntactically incorrect statement?

a)

CARNIV lion, tiger, cat, man, dog;
VEGET minnow, man, dog;
lion EATS man WITH dog; 	dog is carniv & veget
lion WITH tiger EATS man;	man is carniv & veget
minnow IS EATEN BY cat  	carniv may not eat veget

b)

VEGETABLE onions, leeks;
VEGET Fred, Albert;
Fred HATES onions WITH leeks;
BEGIN Fred EATS onions; Albert EATS leeks; END
CARNIV lion; Albert IS EATEN BY lion	CARNIV may not EAT VEGET
AND lion EATS onions;   	CARNIV may not EAT VEGETABLE
onions IS EATEN BY
Fred WITH leeks;        	VEGETABLE (leeks) may not EAT VEGETABLE (onions)

c)

MALE Jack; FEMALE Joy; CARNIV Joy;
Jack LOVES Joy; Joy HATES Jack;
Jack IS EATEN BY Joy; lion EATS Jack WITH Joy;	lion undeclared
lion LOVES Jack with Joy;	lion, JackwithJoy undeclared [spaces ignored!]
Jack AND Joy HATES lion;	lion undeclared