FINALLY, HE WOULD GIVE AS A FINAL ANSWER ONETYPE 3

Q2: When the U.N. Security Council ordered

of a taxonomy for temporal questions. Section 3

a global embargo on trade with Iraq?

describes the general architecture of our temporal

Q.A. system. Section 4 deepens into the first part

Type 4: Multiple events temporal questions with-

of the system: the decomposition unit. Finally, the

out temporal expression. Questions that consist

evaluation of the decomposition unit and some con-

of two or more events, related by a temporal sig-

clusions are shown.

nal. This signal establishes the order between the

events in the question. Example: “What happened

2 Proposal of a Temporal Questions

to world oil prices after the Iraqi annexation of

Taxonomy

Kuwait?”. In this example, the temporal signal is

Before explaining how to answer temporal ques-

after and the question would be decomposed into:

tions, it is necessary to classify them, since the

Q2: When did the Iraqi “annexation” of

questions and complex questions. We will consider

Kuwait occur?

as simple those questions that can be solved directly

How to process each type will be explained in de-

by a current General Purpose Question Answering

tail in the following sections.

system, since they are formed by a single event. On

the other hand, we will consider as complex those

3 Multi-layered Question-Answering

questions that are formed by more than one event

System Architecture

related by a temporal signal which establishes an

Current Question Answering system architectures

order relation between these events.

do not allow to process complex questions. That is,

Simple Temporal Questions:

questions whose answer needs to be gathered from

Type 1: Single event temporal questions without

pieces of factual information that is scattered in a

temporal expression (TE). This kind of questions

document or through different documents. In or-

are formed by a single event and can be directly

der to be able to process these complex questions,

resolved by a Q.A. System, without pre- or post-

we propose a multi-layered architecture. This ar-

processing them. There are not temporal expres-

chitecture increases the functionality of the current

sions in the question. Example: “When did Jordan

Question-Answering systems, allowing us to solve

close the port of Aqaba to Kuwait?”

any type of temporal questions. Moreover, this sys-

Type 2: Single event temporal questions with tem-

poral expression. There is a single event in the ques-

tem could be easily augmented with new layers to

cope with questions that need complex processing

The main advantages of performing this multi-

and are not temporal oriented.

layered system are:

Some examples of complex questions are:

Temporal questions like “Where did Michael

Milken study before going to the University of

output of the processing layer to the type of

Pennsylvania?”. This kind of questions needs

input that the Q.A. system uses.

to use temporal information and event ordering

Script questions like “How do I assemble a bi-

not necessary to modify the Q.A. system when

cycle?”. In these questions, the final answer is

you want to deal with more complex questions.

a set of ordered answers.

Template-based questions like “Which are the

main biographical data of Nelson Mandela?”.

questions within the type accepted by that

This question should be divided in a number of

layer.

factual questions asking for different aspects of

Nelson Mandela’s biography. Gathering their

Next, we present a layer oriented to process tem-

respective answers will make it possible to an-

poral questions according to the taxonomy shown in

swer the original question.