Directory[] gives the current working directory.
DistributionParameterAssumptions[dist] gives a logical expression for assumptions on parameters in the symbolic distribution dist.
Divide
(Built-in Mathematica Symbol) x/y or Divide[x, y] is equivalent to x y^-1.
Divisible[n, m] yields True if n is divisible by m, and yields False if it is not.
EditDistance[u, v] gives the edit or Levenshtein distance between strings or vectors u and v.
EndOfFile is a symbol returned by Read when it reaches the end of a file.
ErrorBoxOptions -> {opt_1 -> val_1, opt_2 -> val_2, ...} applies options and corresponding values.
EvaluationCompletionAction is an option for notebooks that specifies the action taken when an evaluation is completed.
ExportString[expr, " format"] generates a string corresponding to expr exported in the specified format. ExportString[rules, {"format", "Rules"}] gives explicit rules for ...
FindGraphIsomorphism[g_1, g_2] finds an isomorphism that maps the graph g_1 to g_2 by renaming vertices.