The Superposition Theorem is a fundamental principle in electrical engineering used to analyze linear circuits that contain multiple independent sources (such as voltage or current sources). The theorem states that in a linear circuit with more than one independent source, the response (voltage or current) at any point in the circuit can be found by considering each independent source separately while all other independent sources are turned off (inactive).
Plastics are a wide range of synthetic or semi-synthetic materials made from polymers, which are large molecules composed of repeating structural units called monomers. These materials are typically derived from petrochemicals and can exhibit a variety of properties depending on their composition and how they are processed. ### Categories of Plastics: 1. **Thermoplastics**: These plastics can be melted and reformed multiple times without significant chemical change.
Ground granulated blast-furnace slag (GGBS or GGBF slag) is a byproduct from the iron-making industry. It is produced by rapidly cooling molten iron slaga waste material generated during the extraction of iron from iron ore in a blast furnace—using water or steam, which results in the formation of a glassy granulated material. This granulated slag is then dried and finely ground to create a powdery substance.
Petroleum jelly, also known as petrolatum or soft paraffin, is a semi-solid mixture of hydrocarbons derived from petroleum. It has a thick, gooey consistency and is typically colorless or pale yellow. Petroleum jelly is widely used in various applications, including: 1. **Moisturizer**: It's commonly used as a skin moisturizer to help prevent dryness and to protect minor cuts, burns, and chapped skin.
Slag is a byproduct generated during the process of smelting, which is the extraction of metal from its ore. It consists primarily of the inorganic impurities that are removed from the metal during processing. When ores are heated to high temperatures, the metal melts and separates from the unwanted materials, which then combine to form slag. Slag typically consists of a mixture of various compounds, including oxides of silicon, aluminum, calcium, magnesium, and iron.
If is the change of basis matrix, then the matrix representation of a bilinear form that looked like:
then the matrix in the new basis is:
Sylvester's law of inertia then tells us that the number of positive, negative and 0 eigenvalues of both of those matrices is the same.
Proof: the value of a given bilinear form cannot change due to a change of basis, since the bilinear form is just a function, and does not depend on the choice of basis. The only thing that change is the matrix representation of the form. Therefore, we must have:
and in the new basis:
and so since:
Symmetric bilinear map by Ciro Santilli 40 Updated 2025-07-16
Subcase of symmetric multilinear map:
Requires the two inputs and to be in the same vector space of course.
The most important example is the dot product, which is also a positive definite symmetric bilinear form.
It takes as input three vectors, and outputs one real number, the volume. And it is linear on each vector. This perfectly satisfied the definition of a tensor of order (3,0).
Given a basis and a function that return the volume of a parallelepiped given by three vectors , .
So, by taking , we understand that two matrices being congruent means that they can both correspond to the same bilinear form in different bases.

Pinned article: Introduction to the OurBigBook Project

Welcome to the OurBigBook Project! Our goal is to create the perfect publishing platform for STEM subjects, and get university-level students to write the best free STEM tutorials ever.
Everyone is welcome to create an account and play with the site: ourbigbook.com/go/register. We belive that students themselves can write amazing tutorials, but teachers are welcome too. You can write about anything you want, it doesn't have to be STEM or even educational. Silly test content is very welcome and you won't be penalized in any way. Just keep it legal!
We have two killer features:
  1. topics: topics group articles by different users with the same title, e.g. here is the topic for the "Fundamental Theorem of Calculus" ourbigbook.com/go/topic/fundamental-theorem-of-calculus
    Articles of different users are sorted by upvote within each article page. This feature is a bit like:
    • a Wikipedia where each user can have their own version of each article
    • a Q&A website like Stack Overflow, where multiple people can give their views on a given topic, and the best ones are sorted by upvote. Except you don't need to wait for someone to ask first, and any topic goes, no matter how narrow or broad
    This feature makes it possible for readers to find better explanations of any topic created by other writers. And it allows writers to create an explanation in a place that readers might actually find it.
    Figure 1.
    Screenshot of the "Derivative" topic page
    . View it live at: ourbigbook.com/go/topic/derivative
  2. local editing: you can store all your personal knowledge base content locally in a plaintext markup format that can be edited locally and published either:
    This way you can be sure that even if OurBigBook.com were to go down one day (which we have no plans to do as it is quite cheap to host!), your content will still be perfectly readable as a static site.
    Figure 2.
    You can publish local OurBigBook lightweight markup files to either https://OurBigBook.com or as a static website
    .
    Figure 3.
    Visual Studio Code extension installation
    .
    Figure 4.
    Visual Studio Code extension tree navigation
    .
    Figure 5.
    Web editor
    . You can also edit articles on the Web editor without installing anything locally.
    Video 3.
    Edit locally and publish demo
    . Source. This shows editing OurBigBook Markup and publishing it using the Visual Studio Code extension.
    Video 4.
    OurBigBook Visual Studio Code extension editing and navigation demo
    . Source.
  3. https://raw.githubusercontent.com/ourbigbook/ourbigbook-media/master/feature/x/hilbert-space-arrow.png
  4. Infinitely deep tables of contents:
    Figure 6.
    Dynamic article tree with infinitely deep table of contents
    .
    Descendant pages can also show up as toplevel e.g.: ourbigbook.com/cirosantilli/chordate-subclade
All our software is open source and hosted at: github.com/ourbigbook/ourbigbook
Further documentation can be found at: docs.ourbigbook.com
Feel free to reach our to us for any help or suggestions: docs.ourbigbook.com/#contact