====== Task 1.a - Concrete Noun Categorization ======


==== Introduction ====

The goal of the sub-task is to group concrete nouns into semantic categories.

The {{concnouns.categorization.dataset.txt.gz |data set}} consists of 44 concrete nouns, belonging to 6 semantic categories (four animates and two inanimates). The nouns are included in the feature norms described in McRae et al. (2005) (cf. [[comparison_with_speaker-generated_features|Task3]]).


==== Task Operationalization ====

We operationalize concrete noun categorization as a clustering task. Since the data set is organized hierarchically,
we will run three clustering experiments, varying the number of classes and consequently their level of generality:

  * **6-way clustering** - models will be tested on their ability to categorize the nouns into the most fine-grained classes of the dataset: //bird// ("peacock"), //groundAnimal// ("lion"), //fruitTree// ("cherry"), //green// ("potato"), //tool// ("hammer"), //vehicle// ("car");
  * **3-way clustering** - models will be tested on their ability to categorize the nouns into 3 classes: //animal// (superordinate of //bird// and //groundAnimal//), //vegetable// (superordinate of //fruitTree// and //green//), and //artifact// (superordinate of //tool// and //vehicle//);

  * **2-way clustering** - models will be tested on their ability to categorize the nouns into the two top classes: //natural// (superordinate of //animal// and //vegetable//) and //artifact// (superordinate of //tool// and //vehicle//)

To abstract away from differences stemming from any specific clustering method, you are asked to run your experiments with the //k-means// algorithm available in [[http://glaros.dtc.umn.edu/gkhome/cluto/cluto/overview|CLUTO]]. In case you can not run  [[http://glaros.dtc.umn.edu/gkhome/cluto/cluto/overview|CLUTO]] on your system, the workshop organizers will carry out the clustering for you. In this case, data should be prepared according to a format that will be specified later on. Participants are also invited to experiment with other clustering methods and to compare the results with those obtained with[[http://glaros.dtc.umn.edu/gkhome/cluto/cluto/overview|CLUTO]].


==== Task Evaluation ====

Evaluation will be carried in two stages:

1. **quantitative evaluation** - results will be evaluated with respect to the two measures for cluster quality available in CLUTO: //purity// and //entropy// (cf. Zhao, Y. and G. Karypis (2002), "Evaluation of Hierarchical Clustering Algorithms for Document Datasets", in //CIKM 2002//). 

2. **qualitative evaluation** - participants will be asked to perform a fine-grained error analysis, focussing on critical nouns, hard classes, etc. Details about this type of evaluation will be provided later on.


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