Аннотация
Given a formal context, an ordinal factor is a subset of its incidence
relation that forms a chain in the concept lattice, i.e., a part of the dataset
that corresponds to a linear order. To visualize the data in a formal context,
Ganter and Glodeanu proposed a biplot based on two ordinal factors. For the
biplot to be useful, it is important that these factors comprise as much data
points as possible, i.e., that they cover a large part of the incidence
relation. In this work, we investigate such ordinal two-factorizations. First,
we investigate for formal contexts that omit ordinal two-factorizations the
disjointness of the two factors. Then, we show that deciding on the existence
of two-factorizations of a given size is an NP-complete problem which makes
computing maximal factorizations computationally expensive. Finally, we provide
the algorithm Ord2Factor that allows us to compute large ordinal
two-factorizations.
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