The Modern Mathematics of Deep Learning

Sign classifiers

Penguin learning project

The project uses 342 complete Palmer penguin records: 240 training-pool and 102 held-out rows. The selected training rows determine feature scaling and model parameters. Source CSV

This project trains weights with softmax, unlike the homepage lab, which uses nearest species averages. Same penguin measurements; different classification methods. Predictions can differ.

Prediction rules and layers · Describe or apply prediction rules, layers and parameters.

The project uses a linear rule with two features. The fitted weights produce scores or normalized mass.

Consider this concept alongside the project; its source assumptions may differ. These observations do not prove a theorem.

Input: 12 × 2; Held-out evaluation: 102 · #58 · 40.6 mm, 193 mm. Known answer: Adélie; Prediction: Adélie · [≈0.7383, ≈0.2444, ≈0.01737].

Used in these source sections: 1.2 Learning from examples

Apply the sign rule to each network output: zero counts as positive.

The sign transforms a scalar network output into a binary label.

Source formula example

{\mathcal{F}}_{{{a}},{\operatorname{sgn}}}=\big\{{\operatorname{sgn}}(\Phi_{{a}}(\cdot,\theta))\colon\theta\in{\mathbb{R}}^{P(N)}\big\},\quad\text{where}\quad{\operatorname{sgn}}(x)\coloneqq\begin{cases}\phantom{-}1,&\textup{if }x\geq 0,\\ -1,&\textup{if }x<0.\end{cases}

exact · The toy evaluates the sign rule on three scalar scores.

Symbols

$Fₐ,sgn$: Set of sign classifiers from the network class.
$sgn$: Function returning +1 for nonnegative input and −1 for negative input.
$θ$: Real network parameter vector.

Source formula example

This source example uses its own inputs and assumptions. Editing it does not change the project.

Edit a value or the code, then run the example. This is a finite demonstration, not a proof of the paper’s theorem.

First score

This example’s data flow

You choose

input.score = 1

Calculated here

Result expression: { raw, labels: raw.map((v) => (v >= 0 ? 1 : -1)) }

raw = [input.score, 0, -2] Uses: input.score

Returns

Example result

raw: array (3 items): [1, 0, -2]
labels: array (3 items): [1, 1, -1]

JavaScript

Read numbers from input and return the result. JavaScript basics.

Result

Enable JavaScript to run this example.

Technical statement

The source uses labels +1 and −1 and includes zero in the positive branch.

Source: Source expression