(letrec(lambda(kb)(execute(untilend(tail kb))(head kb)))(execute lambda
(c db)(if(eq c(quote NIL))(quote NIL)(if(isadd(head c))(execute(tail c)
(addset db(eval(arg1(head c))db)(mkatom(arg2(head c)))(eval(arg3(head c
))db)))(if(isdb(head c))(cons db(execute(tail c)db))(cons(eval(head c)db
)(execute(tail c)db))))))(eval lambda(e db)(if(isunion e)(union(eval(arg1
e)db)(eval(arg2 e)db))(if(isinter e)(intersection(eval(arg1 e)db)(eval(
arg2 e)db))(if(isdiff e)(difference(eval(arg1 e)db)(eval(arg2 e)db))(if
(isim e)(imageset(eval(arg1 e)db)(mkatom(arg2 e))db)(if(isinvim e)(invimage
(eval(arg2 e)db)(mkatom(arg1 e))db)(if(isatomlist e)e emptyset)))))))(imageset
lambda(nodeset attr db)(reduce union(map(lambda(n)(image n attr db))nodeset
)emptyset))(image lambda(node attr db)(if(defined node db)(let(if(defined
attr a)(associate attr a)emptyset)(a associate node db))emptyset))(invimage
lambda(nodeset attr db)(filter(lambda(n)(not(eq(intersection(image n attr
db)nodeset)emptyset)))(domain db)))(addset lambda(db ns1 attr ns2)(reduce
(lambda(n db)(addel n attr ns2 db))ns1 db))(addel lambda(node attr nodeset
db)(let(let(update db node(update a attr(union nodeset s)))(s if(defined
attr a)(associate attr a)emptyset))(a if(defined node db)(associate node
db)(quote NIL))))(isunion lambda(e)(and(not(atom e))(eq(head e)(quote union
))))(isinter lambda(e)(and(not(atom e))(eq(head e)(quote inter))))(isdiff
lambda(e)(and(not(atom e))(eq(head e)(quote diff))))(isim lambda(e)(and
(not(atom e))(eq(head e)(quote im))))(isinvim lambda(e)(and(not(atom e)
)(eq(head e)(quote inv))))(isadd lambda(e)(and(not(atom e))(eq(head e)(
quote add))))(isdb lambda(e)(eq e(quote db)))(isatomlist lambda(e)(or(eq
e(quote NIL))(and(not(atom e))(and(atom(head e))(isatomlist(tail e)))))
)(arg1 lambda(e)(if(leq(quote 2)(length e))(head(tail e))(quote NIL)))(
arg2 lambda(e)(if(leq(quote 3)(length e))(head(tail(tail e)))(quote NIL
)))(arg3 lambda(e)(if(leq(quote 4)(length e))(head(tail(tail(tail e))))
(quote NIL)))(mkatom lambda(x)(if(atom x)x(quote NIL))))