CREATE TABLE keyphrase (keyphraseid INT, keyphrasename VARCHAR)
CREATE TABLE writes (paperid INT, authorid INT)
CREATE TABLE paper (paperid INT, title VARCHAR, venueid INT, year INT, numciting INT, numcitedby INT, journalid INT)
CREATE TABLE author (authorid INT, authorname VARCHAR)
CREATE TABLE paperkeyphrase (paperid INT, keyphraseid INT)
CREATE TABLE field (fieldid INT)
CREATE TABLE journal (journalid INT, journalname VARCHAR)
CREATE TABLE dataset (datasetid INT, datasetname VARCHAR)
CREATE TABLE paperdataset (paperid INT, datasetid INT)
CREATE TABLE paperfield (fieldid INT, paperid INT)
CREATE TABLE venue (venueid INT, venuename VARCHAR)
CREATE TABLE cite (citingpaperid INT, citedpaperid INT)

has any paper tried Multiuser Receiver for Decision Feedback ?
SELECT DISTINCT paperkeyphrase.paperid FROM keyphrase, paperkeyphrase WHERE keyphrase.keyphrasename IN ('Multiuser Receiver', 'Decision Feedback') GROUP BY paperkeyphrase.paperid HAVING COUNT(DISTINCT keyphrase.keyphraseid) = 1
SELECT DISTINCT "paperkeyphrase"."paperid" FROM "keyphrase" CROSS JOIN "paperkeyphrase" WHERE "keyphrase"."keyphrasename" IN ('Multiuser Receiver', 'Decision Feedback') GROUP BY "paperkeyphrase"."paperid" HAVING COUNT(DISTINCT "keyphrase"."keyphraseid") = 1