xviii we employ color to emphasize that certain words refer to datasetfunctionor package in python all code is written in typewriter font to be compatible with past notation choiceswe introduced special blue symbol for the model (designmatrix of linear model important notation such as ggis often defined in mnemonic waysuch as for "training" for "guess"gfor the "star(that isoptimalguessand for "losswe will occasionally use bayesian notation convention in which the same symbol is used to denote different (conditionalprobability densities in particularinstead of writing fx (xand fx ( yfor the probability density function (pdfof and the conditional pdf of given ywe simply write (xand ( ythis particular style of notation can be of great descriptive valuedespite its apparent ambiguity general font/notation rules scalar vector random vector matrix set estimate or approximation optimal average common mathematical symbols for all is proportional to is distributed as there exists is perpendicular to iid are independent and identically distributed as approx is approximately distributed as gradient of hessian of is approximately is much smaller than ~~iid cp has continuous derivatives of order is asymptotically direct sum