We performed our experiments using a retrieval system based on Apache Lucene. Furthermore, we implemented BM25 (Okapi). Each of our four submitted runs has been run against an English index, which contains the following fields:

-Patent number (UCID)
-Title (INVENTION-TITLE)
-Abstract (ABSTRACT)
-IPC codes (IPC)

In each of the four experiments, we used the following query constellation:
-title: search in the fields INVENTION-TITLE and ABSTRACT
-ipc codes: search in the fields IPC
-description and mainclaim: search in the field ABSTRACT

Furthermore, in each case we removed stopwords and analyzed the documents of the collection and the topic files (queries) with the help of the Porter Stemmer.

Run 1 (English terms)
In case of the first run, we generated queries on the basis of the title, the mainclaim and the first part of the description, which can be seen as an introduction to the invention. We used phrases as queries, whereas in this case one single term can be seen as a phrase. Furthermore, we included the ipc codes. The ipc codes as well as the phrases extracted from the title, the mainclaim and the first part of the description are combined by boolean operators. A relevant document has to share at least one title phrase, one ipc class and one phrase of the description and the mainclaim.

Run 2 (English terms)
This run has been performed using phrase queries, too. In contrast to the first one, we only extracted phrases from the title. A phrase is not a single term, but consists of at least two terms. For that a title can be quite long, we restricted the number of terms within one phrase to four. In case of titles being longer than this cutoff, the title has been divided into subphrases. The ipc codes as well as the phrases extracted from the title are combined by boolean operators. A relevant document has to share at least one title phrase and one ipc class.

Run 3 (English terms)
This run has been performed using phrase queries. In contrast to the second one, we only extracted phrases from the mainclaim and the first part of the description. A phrase is not a single term, but consists of at least two terms. We restricted the number of terms within one phrase to four. For that the mainclaim and the description  are in general longer than this cutoff, these parts have been divided into subphrases. The ipc codes as well as the phrases extracted from the description and the mainclaim are combined by boolean operators. A relevant document has to share at least one phrase of the mainclaim, one phrase of the description and one ipc class.
  
Run 4 (English terms)
The fourth run has been performed using phrase queries as well. In contrast to the third one, we extracted phrases from the mainclaim, the first part of the description and the title. A phrase is not a single term, but consists of at least two terms. We restricted the number of terms within one phrase to four. For that the mainclaim and the description are in general longer than this cutoff, these parts have been divided into subphrases. In case of a title being longer than four terms, it has been divided into subphrases, too. The ipc codes as well as the phrases extracted from the description, the mainclaim and the title are combined by boolean operators. A relevant document has to share at least one phrase of the mainclaim, one phrase of the description and the title and one ipc class.
