ACM Search with the Keywords "question answering semantics"

I am currently looking at the ACM database of papers. I am using the keywords "question answering semantics." There are about 200 results. The following are some of the first 20 returned. A few of these are quite old and some of them have been returned by other keywords that I have used.

A semantic approach to boost passage retrieval effectiveness for question answering
Bahadorreza Ofoghi, John Yearwood, Ranadhir Ghosh
January 2006

The role of lexico-semantic feedback in open-domain textual question-answering
Sanda Harabagiu, Dan Moldovan, Marius Pas,ca, Rada Mihalcea, Mihai Surdeanu, Raazvan Bunescu, Roxana Gîrju, Vasile Rus, Paul Morarescu
July 2001

Towards light semantic processing for Question Answering
Benjamin Van Durme, Yifen Huang, Anna Kups'c', Eric Nyberg
May 2003

Answer extraction, semantic clustering, and extractive summarization for clinical question answering
Dina Demner-Fushman, Jimmy Lin
July 2006

AquaLog: an ontology-driven question answering system to interface the semantic web
Vanessa Lopez Garcia, Enrico Motta, Victoria Uren
June 2006

Answering Clinical Questions with Knowledge-Based and Statistical Techniques
Dina Demner-Fushman, Jimmy Lin
March 2007

Across human language technologies: Statistical answer-type identification in open-domain question answering
John Prager, Jennifer Chu-Carroll, Krzysztof Czuba
March 2002

Experiments with open-domain textual Question Answering
Sanda M. Harabagiu, Marius A. Pas,ca, Steven J. Maiorano
July 2000

Answering English questions by computer: a survey
R. F. Simmons
January 1965

Helpful answers to modal and hypothetical questions
Anne De Roeck, Richard Ball, Keith Brown, Chris Fox, Marjolein Groefsema, Nadim Obeid, Ray Turner
April 1991

IR-7 (information retrieval): natural language processing for IR: Unsupervised question answering data acquisition from local corpora
Lucian Vlad Lita, Jaime Carbonell
November 2004

Question and answering: Answering complex questions with random walk models
Sanda Harabagiu, Finley Lacatusu, Andrew Hickl
August 2006

High performance question/answering
Marius A. Pasca, Sandra M. Harabagiu
September 2001

Extracting exact answers to questions based on structural links
Wei Li, Rohini K. Srihari, Xiaoge Li, M. Srikanth, Xiuhong Zhang, Cheng Niu
August 2002

Automatic detection of causal relations for Question Answering
Roxana Girju
July 2003

Performance issues and error analysis in an open-domain question answering system
Dan Moldovan, Marius Pas,ca, Sanda Harabagiu, Mihai Surdeanu
April 2003

An analysis of clarification dialogue for question answering
Marco De Boni, Suresh Manandhar
May 2003

The use of theorem-proving techniques in question-answering systems
C. Cordell Green, Bertram Raphael
January 1968