Sparse RBM was proposed to enable sparse representations. Groups are either sparse or dense mode; Interfaces can be either. Early work included simulating ad hoc mobile networks on sparse and densely connected topologies. There are several variations to the basic sparse approximation problem. Side one consisted of a tape loop system for generating music from relatively sparse input. The central Sahara is hyperarid, with sparse vegetation. It has a melancholy feel and rather sparse arrangements. It is used in robust data analysis and sparse coding. Godflesh lyrics are cryptic, bleak and generally sparse. Foliage may become small, sparse and yellowed. The summer fur is short, sparse and coarse. Both iterative and direct methods exist for sparse matrix solving. Special algorithms have been developed for factorizing large sparse matrices. LSI also deals effectively with sparse, ambiguous, and contradictory data. Larvae are primarily green, with sparse hairs.