Adaptive Information Filtering: Learning Drifting Concepts

The task of information filtering is to classify texts from a stream of documents into relevant and non relevant, respectively, with respect to a particular category or user interest, which may change over time. A filtering system should be able to adapt to such concept changes. This paper explores methods to recognize concept changes and to maintain windows on the training data, whose size is either fixed or automatically adapted to the current extent of concept change. Experiments with two simulated concept drift scenarios based on real-world text data and eight learning methods are performed to evaluate three indicators for concept changes and to compare approaches with fixed and adjustable window sizes, respectively, to each other and to learning on all previously seen examples. Even using only a simple window on the data already improves the performance of the classifiers significantly as compared to learning on all examples. For most of the classifiers, the window adjustments lead to a further increase in performance compared to windows of fixed size. The chosen indicators allow to reliably recognize concept changes.

Adaptive Drift Analysis

We show that, for any c>0, the (1+1) evolutionary algorithm using an arbitrary mutation rate p_n = c/n finds the optimum of a linear objective function over bit strings of length n in expected time Theta(n log n). Previously, this was only known for c at most 1. Since previous work also shows that universal drift functions cannot exist for c larger than a certain constant, we instead define drift functions which depend crucially on the relevant objective functions (and also on c itself). Using these carefully-constructed drift functions, we prove that the expected optimisation time is Theta(n log n). By giving an alternative proof of the multiplicative drift theorem, we also show that our optimisation-time bound holds with high probability.

Brian O'Meara (hurler)

Career

O'Meara was a member of the county minor hurling panel in 2008 and won a Munster Under 21 Football medal with Tipperary in 2010, lining out at full-forward in the Munster Final against Kerry, to claim Tipperary's first ever title. On 27 May 2010, O'Meara was named to make his debut as full forward in the Tipperary Senior Hurling Team to play Cork in the Munster Senior Hurling Championship quarter-final in Páirc Uí Chaoimh on 30 May 2010. Tipperary ended up losing the game by 3–15 to 0–14, with O'Meara being substituted in the 43rd minute without scoring in the game. On 28 July 2010, O'Meara played at full-forward for Tipperary as they defeated Clare in the 2010 Munster Under-21 Hurling final at Semple Stadium, winning by 1–22 to 1–17.

On 5 September 2010, O'Meara was a non-playing substitute as Tipperary won their 26th All Ireland title, beating reigning champions Killkenny by 4–17 to 1–18 in the final, preventing Kilkenny from achieving an historic 5-in-a-row, it was O'Meara's first All-Ireland winners medal. Six day's later on 11 September 2010, Tipperary clinched the All Ireland Under-21 title by defeating Galway by 5–22 to 0–12 at Semple Stadium, with O'Meara starting at full forward and winning the man of the match award.

Adaptive Drift

Brian O'Meara (hurler)

Career

O'Meara was a member of the county minor hurling panel in 2008 and won a Munster Under 21 Football medal with Tipperary in 2010, lining out at full-forward in the Munster Final against Kerry, to claim Tipperary's first ever title. On 27 May 2010, O'Meara was named to make his debut as full forward in the Tipperary Senior Hurling Team to play Cork in the Munster Senior Hurling Championship quarter-final in Páirc Uí Chaoimh on 30 May 2010. Tipperary ended up losing the game by 3–15 to 0–14, with O'Meara being substituted in the 43rd minute without scoring in the game. On 28 July 2010, O'Meara played at full-forward for Tipperary as they defeated Clare in the 2010 Munster Under-21 Hurling final at Semple Stadium, winning by 1–22 to 1–17.

On 5 September 2010, O'Meara was a non-playing substitute as Tipperary won their 26th All Ireland title, beating reigning champions Killkenny by 4–17 to 1–18 in the final, preventing Kilkenny from achieving an historic 5-in-a-row, it was O'Meara's first All-Ireland winners medal. Six day's later on 11 September 2010, Tipperary clinched the All Ireland Under-21 title by defeating Galway by 5–22 to 0–12 at Semple Stadium, with O'Meara starting at full forward and winning the man of the match award.