Erhu by Ciro Santilli 40 Updated 2025-07-16
Figure 1.
A blind erhu street performer playing in Jingzhou, Hubei (2006)
Source. Playing the erhu is a traditional occupation for blind people in China, a notable example being Abing.
Video 2.
The 12 Most Famous Erhu Melodies in China (2021)
Source. TODO transcribe list.
Algebraic analysis is a branch of mathematics that involves the study of analytical problems using algebraic methods. It combines techniques from algebra, particularly abstract algebra, and analysis to investigate mathematical structures and their properties. This discipline can be particularly relevant in several areas, including: 1. **Algebraic Analysis of Differential Equations**: This involves studying solutions to differential equations using tools from algebra. For example, one might analyze differential operators in terms of their algebraic properties.
Eck Masters does not appear to be a widely recognized term or concept as of my last knowledge update in October 2023. It could refer to a specific program, entity, or concept that may have emerged after that date or may be niche or regional in nature.
"Human Shadow Etched in Stone" is not a widely recognized term or concept as of my last knowledge update in October 2023. It could refer to various artistic interpretations, geological formations, or metaphorical ideas. It may be a title of artwork, a phrase from literature, or even refer to a specific feature in geology or archaeology.
The concept of an "exceptional inverse image functor" comes from the context of category theory, particularly in the study of sheaves and toposes. It is often studied in relation to the behavior of inverse image functors in different categorical contexts.
Casa Ricordi is a historic music publishing company based in Milan, Italy. Founded in 1808 by Giovanni Ricordi, it has played a significant role in the development of music publishing and the promotion of opera and classical music. The company is known for publishing works by many notable composers, including Giuseppe Verdi, Giacomo Puccini, and others who contributed to the Italian operatic tradition.
Church, Paxson & Co. is a firm that was historically known for its investment banking and financial services. The firm has roots that trace back to the early 20th century and has engaged in various financial activities such as underwriting, mergers and acquisitions, and other advisory services. However, the specific details about its current operations or structure might not be readily available as it could vary over time or due to changes in the industry.
Robert Cocks & Co. was a notable British music publishing company established in the early 19th century, in 1824, by Robert Cocks. The company produced a wide array of music sheets and scores, particularly for brass band and military music, and it played a significant role in the dissemination of music during its time. It became well-known for publishing works by various composers and contributed to the music culture of the period. Robert Cocks & Co.
James Hewitt is a British musician, often known for his work as a composer and pianist. He may not be as widely recognized as some mainstream artists, but he has made contributions to various music projects and has been involved in the music industry in different capacities. His works may cover diverse genres and styles, reflecting a deep understanding of musical composition and performance.
Joseph Carr was a prominent music publisher and entrepreneur in the early to mid-20th century, best known for his work in the publishing of popular music. He was associated with various other publishers and musicians in the industry and played a significant role in promoting and distributing sheet music. Carr was also notable for his efforts in the field of music education and provided resources for musicians and educators.
Lu Ann Simms is a singer and songwriter who gained popularity in the 1950s and 1960s. She is best known for her work in the genre of pop music and her catchy hits during that era. Simms also had a notable presence on television, appearing on various variety shows and music programs. Beyond her music career, she is recognized for her contributions to the entertainment industry and her distinctive vocal style.
Matthäus Waissel does not appear to be a widely recognized figure in public knowledge as of my last update in October 2023. It is possible that he could be a private individual, a character from literature or media, or a figure who has gained prominence after that date.
Effective field theory by Ciro Santilli 40 Updated 2025-07-16
www.youtube.com/watch?v=WB8r7CU7clk&list=PLUl4u3cNGP60TvpbO5toEWC8y8w51dtvm by Iain Stewart. Basically starts by explaining how quantum field theory is so generic that it is hard to get any numerical results out of it :-)
But in particular, we want to describe those subtheories in a way that we can reach arbitrary precision of the full theory if desired.

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