The number of features in a tabular dataset. Typically is used, but sometimes is required to distinguish two datasets.
The dimensionality of a matrix (dataset) has rows (observations) and columns (features).
The vertex set in a graph.
The edge set in a graph.
The vertex in a graph.
The edge in a graph.
Depending on the context may be interpreted as follows:
The -norm of a vector ,
Sign function for ,
In the description of an algorithm, this typically denotes the -th feature vector in the inference set.
In the description of an algorithm, this typically denotes the -th response that needs to be predicted by the inference algorithm given the feature vector from the inference set.