Notebooks[] gives a list of notebooks currently open in the front end.
Overscript[x, y] is an object that formats as OverscriptBox[x, y].
ParallelSum[expr, {i, i_max}] evaluates in parallel the sum \[Sum]i = 1 i_max expr.ParallelSum[expr, {i, i_min, i_max}] starts with i = i min.ParallelSum[expr, {i, i_min, ...
PermutationProduct[a, b, c] gives the product of permutations a, b, c.
PolynomialQ[expr, var] yields True if expr is a polynomial in var, and yields False otherwise. PolynomialQ[expr, {var_1, ...}] tests whether expr is a polynomial in the var_i.
PreserveImageOptions is an option to graphics and related functions that specifies whether image size and certain other options should be preserved from the previous version ...
PrintingOptions -> {opt_1 -> val_1, opt_2 -> val_2, ...} is an option that specifies settings for printing.
RandomImage[max, {w, h}] gives an image of dimensions {w, h} with pseudorandom pixel values generated from a uniform distribution in the range 0 to max.RandomImage[{min, ...
RandomInteger[{i_min, i_max}] gives a pseudorandom integer in the range {i_min, i_max}. RandomInteger[i_max] gives a pseudorandom integer in the range {0, ...
RecordSeparators is an option for Read, Find, and related functions that specifies the list of strings to be taken as delimiters for records.