Solutions for exercise set # 7 (given both in Lisp and in SQL):

LISP

;
;	Find details of all projects in London
;
(setq ans1 (retrieve '(
	((j (jno jname)))
	(equal (j city) 'london))))
(format t "Ans 1: ~s ~%" ans1)
;
;	Find JNAME values for projects supplied by supplier S1
;
(setq ans2 (retrieve '(
	((j (jname)))
	(exists spj
		(and (equal (spj sno) 's1)
			(equal (spj jno) (j jno))
		)
	))))
(format t "Ans 2: ~s ~%" ans2)
;
;	Get supplier name values for suppliers who supply project J1 
;
(setq ans3 (retrieve '(
	((s (sname)))
	(exists spj
		(and
			(equal (spj jno) 'j1)
			(equal (spj sno) (s sno))
		)
	))))
(format t "Ans 3: ~s ~%" ans3)
;
;	Get supplier name values for suppliers who supply a 
;		London project with a red part 
;
(setq ans4 (retrieve '(
	((s (sname)))
	(exists j
		(exists p
			(exists spj 
			(and (equal (p color) 'red)
				(and (equal (j city) 'london)
					(and (equal (s sno) (spj sno))
						(and (equal (p pno) (spj pno))
							(equal (j jno) (spj jno))
						)
					)
				)
			))
		)))))
(format t "Ans 4: ~s ~%" ans4)
;
;	Get the names of parts used on every London project 
;
(setq ans5 (retrieve '(
	((p (pname)))
	(forall j
		(exists spj
			(implies (equal (j city) 'london)
				(and (equal (p pno) (spj pno))
					(equal (j jno) (spj jno))
				)
			)
		)
	))))
(format t "Ans 5: ~s ~%" ans5)
;
;	That's all, folks!
;

SQL

/*
	Solutions in SQL.

	Find details of all projects in London
*/
select jno, jname
	from j
	where city = 'LONDON';
/*
	Find JNAME values for projects sppplied by
	supplier S1
*/
select distinct JNAME
	from j, spj
	where j.jno = spj.jno
		and spj.sno = 'S1';
/*
	Find supplier names for suppliers who
	supply project J1
*/
select distinct sname
	from s, spj
	where spj.jno = 'J1'
	and spj.sno = s.sno;
/*
	Get supplier name values for suppliers who
	supply a London project with a red part.
*/
select distinct sname
	from s, p, j, spj
	where p.color = 'RED'
		and j.city = 'LONDON'
		and s.sno = spj.sno
		and p.pno = spj.pno
		and j.jno = spj.jno;
/*
	Get the names of parts used on every
	LONDON project.
*/
select distinct pname
	from p
	where not exists
	(select *
		from j
		where j.city = 'LONDON'
		and not exists
			(select *
			from spj
			where p.pno = spj.pno
			and j.jno = spj.jno));
/*
	That's all, folks!
*/