Math & Science ⇒ line-by-line annotation for proofs?

[decitrig]

I'm looking for some way to annotate proofs line by line, as in the following:

statement = statement by theorem blah
= manipulated statement by this property
< something else by definition

etc (note, the equals and the "by"s should be aligned). Are tables the best way to do this, or is there an environment for this? If tables are the solution, I would love it if people could post some snippets of how to do this in a clean-looking way.

--
decitrig

[localghost]

If the text represents math expressions, use the align environment from amsmath. However, be a bit more specific on what you want to do.

There's a reply that still awaits your reaction [1]. It is a matter of politeness to give feedback on provided solutions.

[1] View topic: Specify shorter author name for in-text citations?


Best regards
Thorsten

[gmedina]

Hi,

another option could be the alignat environment provided by amsmath:

Code: Select all

\documentclass{article}
\usepackage{amsmath}

\begin{document}

\begin{alignat}{2}
A\cup(B\cap C) &= (A\cup B)\cap (A\cup C) &\quad &\text{by distributive law.}\\
&= (B\cup A)\cap (C\cup A) &&\text{by commutative law.}\\
&= (B\cap C)\cup A &&\text{by distributive law.}\\
\end{alignat}

\end{document}

[decitrig]

If the text represents math expressions, use the align environment from amsmath. However, be a bit more specific on what you want to do.

There's a reply that still awaits your reaction [1]. It is a matter of politeness to give feedback on provided solutions.

[1] View topic: Specify shorter author name for in-text citations?

Best regards
Thorsten

OT indeed there is. Apologies, it slipped my mind. Fixing now.

[decitrig]

Hi,

another option could be the alignat environment provided by amsmath:

That worked very well - stupid of me not to see that in the docs.

If the text represents math expressions, use the align environment from amsmath. However, be a bit more specific on what you want to do

I did the following:

Code: Select all

% how very contrived this example is
\begin{align}
x^n &= x\cdot x^{n-1} & \mbox{by algebra}
\end{align}

But all the mboxes were right-aligned. The alignat worked perfectly, though.

[frabjous]

Using a double && for the last one should left-align it for you (just as gmedina is doing for alignat):

Code: Select all

\documentclass{article}
\usepackage{amsmath}
\begin{document}
\begin{align}
x^n &= x\cdot x^{n-1} && \mbox{by algebra} \\
x^n + 1 &= x\cdot x^{n-1} + 1 && \mbox{by more algebra} \\
x^n + 1 - n &= x\cdot x^{n-1} + 1 - n && \mbox{by even more algebra}
\end{align}
\end{document}