SELECT E$\_$Fname, E$\_$Lname

FROM EMPLOYEEs

WHERE NOT EXISTS $($

SELECT $1$

FROM research

WHERE EMPLOYEEs.Research$\_$ID $=$ research.Research$\_$ID

$)$;

for this query optimize it using tree:

a$)$ Specify the initial canonical query tree that corresponds to the query.

b$)$ Use query$-$processing steps to construct the suitable query tree for each SQL statement.

i$)$ Remove duplicate projection

ii$)$ Remove unnecessary group concatenation