3.6. Meta-keywords attached to the keywords

This section explains the meaning of the meta-keywords attached to the keywords of the catalogue. Keywords are usually associated with a single meta-keyword, except some that are linked to the meta-keyword modelling exercises and to one other meta-keyword like modelling or puzzles (e.g., see the keywords magic series or degree of diversity of a set of solutions). For each meta-keyword it first gives the list of keywords using the corresponding meta-keyword and then defines the meta-keyword. At present the following meta-keywords are in use.