ctheorems / typst-theorems

An implementation of numbered theorem environments in typst. Available as ctheorems in the official Typst universe. Import with

#import "@preview/ctheorems:2.0.0": *
#show: thm-rules        // Must include!

A standard set of theorem environments in the AMS style is available using

#import thm-themes.ams: *

Features

A theorem environment combines content with automatically updated numbering information. Theorem environments can

• share the same counter (Theorems and Lemmas often do so)
• have their counters attached to headings or other environments (Corollaries are often numbered based upon the parent Theorem)
• be <label>-ed and @reference-d
• be restated or deferred to later in the document.

This package also introduces a few miscellaneous features related to mathematical writing.

• Proof environments, with QED symbols.
• Equation tags (in the manner of LaTeX's \tag).
• Predefined sets of commonly used theorem environments, and a few themes.

Manual and Examples

Get acquainted with ctheorems by checking out the minimal example below!

You can read the manual for a full walkthrough of functionality offered by this module.

Preamble

#import "@preview/ctheorems:2.0.0": *
#import thm-state: thm-restate
#import thm-themes.ams: *
#show: thm-rules.with(qed-symbol: $square$)

#set page(width: 16cm, height: auto, margin: 1.5cm)
#set heading(numbering: "1.")
#show heading: set block(below: 1em)

#let theorem = theorem.with(
  outset: 1em,
  spacing: 2em,
  fill: rgb("#eeffee"),
)

Document

= Random variables

#definition[Expectation][
  The expectation of a random variable $X$ on a probability space $(Omega, cal(E), PP)$ is $
    EE[X] = integral X dif PP,
  $ whenever well-defined.
] <expectation>

#remark[
  We require at least one of $EE[X^+], EE[X^-]$ to be finite.
]

#proposition[
  For any $A in cal(E)$, $
    PP(X in A) = EE[bold(1)_A (X)].
  $
] <prob-exp>

#theorem[Markov][
  Let $X >= 0$. For all $a > 0$, $
    PP(X > a) <= EE[X] / a.
  $
] <markov>
#proof([of @markov], defer: true)[
  $
    PP(X > a)
      &= EE[bold(1)_((a, oo))(X)]   #tag[(@prob-exp)] \
      &<= EE[(X / a) bold(1)_((a, oo))(X)] \
      &<= EE[X] / a. #qedhere
  $
]

#corollary[Chebyshev][
  Let $EE[X] = mu$, $"var"[X] = sigma^2$. Then, $
    PP(|X - mu| >= k sigma) <= 1 / k^2.
  $
] <chebyshev>


#counter(heading).update(0)
#set heading(numbering: "A.")
= Appendix

#thm-restate()

Changelog

v2.0.0

• Breaking changes: complete overhaul of names and syntax.
• Added 'themes' with commonly used theorem environments predefined.
• Introduced equation tagging.
• Added commands for restating theorem environments, useful for creating outlines and deferring proofs to later sections.
• Separated counter handling into thm-counter.

v1.1.3

• Fixed alignment and block-breaking issues resulting from breaking changes in Typst 0.12.

v1.1.2

• Introduced the thmproof function for creating proof environments.
• Inserting #qedhere in a block equation/list/enum item (in a proof) places the qed symbol on the same line. The qed symbol can be customized via thmrules.

v1.1.1

• Extra named arguments given to a theorem environment produced by thmbox (or thmplain) are passed to block.

v1.1.0

• The supplement (for references) is no longer set in thmenv. It can be passed to the theorem environment directly, along with refnumbering to control the appearance of @references.
• Extra named arguments given to thmbox are passed to block.
• Fixed spacing bug for unnumbered environments.
• Replaced dummy figure with labelled metadata.

v1.0.0

• Extra named arguments given to a theorem environment are passed to its formatting function fmt.
• Removed thmref, introduced normal <label>s and @references.
• Import must be followed by show: thmrules.
• Removed name: ... from theorem environments; use #theorem("Euclid")[] instead of #theorem(name: "Euclid")[].
• Theorems are now wrapped in figures.

Acknowledgements

Thanks to

• MJHutchinson for suggesting and implementing the base-level and base: none features,
• rmolinari for suggesting and implementing the separator: ... feature,
• DVDTSB for contributing
  • the idea of passing named arguments from the theorem directly to the fmt function.
  • the number: ... override feature.
  • the title: ... override feature in thm-box.
• PgBiel for fixing breaking changes in version updates.
• The authors of the LaTeX packages amsthm, thmtools, apxproof.
• The awesome devs of typst.app for their support.