# How to achieve two levels of indentation inside align environment?

I'm trying to indent an equation further away - basically to achieve two levels of indentation.
Let me explain a little bit more...

I have the following:

\documentclass{article}

\usepackage{parskip}
\usepackage{amssymb}
\usepackage[fleqn]{amsmath}

\begin{document}

Suppose we want to compute $\nu(u_1)$, we first consider $Y_1$.\\ So $Y_1=A\setminus S_1=\{country, genre\}$, and we have that:\\
\begin{align*}
\nu(u_1)&=\exists(country, genre)(u\,'_1\wedge u\,'_2\wedge u\,'_3)\\
&=\exists(country, genre)(\varphi\,'_1(cd, member, band)\wedge\\
&\varphi\,'_2(cd,member, date)\wedge\\
&\varphi\,'_3(cd, member,country))
\end{align*}

We now want to prove that similarity conditions hold for these three functions we defined.\\

\end{document}


Which produces this: Now, what I want is to indent the third and fourth lines in this equation further, so they will be aligned with the \varphi\,'_1.

I tried to adopt the approach suggested here, and added double && to add a level of indentation:

\documentclass{article}

\usepackage{parskip}
\usepackage{amssymb}
\usepackage[fleqn]{amsmath}

\begin{document}

Suppose we want to compute $\nu(u_1)$, we first consider $Y_1$.\\ So $Y_1=A\setminus S_1=\{country, genre\}$, and we have that:\\
\begin{align*}
\nu(u_1)&=\exists(country, genre)(u\,'_1\wedge u\,'_2\wedge u\,'_3)\\
&=\exists(country, genre)(&&\varphi\,'_1(cd, member, band)\wedge\\
&   &&\varphi\,'_2(cd,member, date)\wedge\\
&   &&\varphi\,'_3(cd, member,country))
\end{align*}

We now want to prove that similarity conditions hold for these three functions we defined.\\

\end{document} Although the three \varphi's are now aligned together, they are unnecessarily pushed further away to the right, and this is obviously not what I intended...

How can I achieve second level of indention correctly?

Any help would be greatly appreciated. \documentclass{article}

\usepackage{parskip}
\usepackage{amssymb}
\usepackage[fleqn]{amsmath}

\begin{document}

Suppose we want to compute $\nu(u_1)$, we first consider $Y_1$.\\
So $Y_1=A\setminus S_1=\{\mathit{country}, \mathit{genre}\}$, and we have that:\\
\begin{align*}
\nu(u_1)&=\exists(\mathit{country}, \mathit{genre})(u\,'_1\wedge u\,'_2\wedge u\,'_3)\\
&=\exists(\mathit{country}, \mathit{genre})(
\!\begin{aligned}[t]
&\varphi\,'_1(\mathit{cd}, \mathit{member}, band)\wedge\\
&        \varphi\,'_2(\mathit{cd},\mathit{member}, date)\wedge\\
&        \varphi\,'_3(\mathit{cd}, \mathit{member},\mathit{country}))
\end{aligned}
\end{align*}

We now want to prove that similarity conditions hold for these
three functions we defined.

\end{document}


You can use split or aligned within the align but note don't use math italic for multi-letter identifiers, and don't end a paragraph with \\

• @yo' yes done (didn't remake image) – David Carlisle Jan 3 '15 at 18:44
• @so.very.tired Please remark that the answer got edited, \! was added before \begin{aligned} to remove the spurious space. – yo' Jan 3 '15 at 19:09
• note that the \! is not needed any more in recent amsmath releases (although it is OK to leave it there, it does not affect the spacing) – David Carlisle Jun 8 '19 at 9:34

The result can likewise be obtained from the OP's 1st MWE by simply making the \varphi lines a \Longunderstack, as follows:

\documentclass{article}

\usepackage{parskip}
\usepackage{amssymb}
\usepackage[fleqn]{amsmath}
\usepackage[usestackEOL]{stackengine}
\stackMath
\begin{document}

Suppose we want to compute $\nu(u_1)$, we first consider $Y_1$.\\ So $Y_1=A\setminus S_1=\{country, genre\}$, and we have that:\\
\begin{align*}
\nu(u_1)&=\exists(country, genre)(u\,'_1\wedge u\,'_2\wedge u\,'_3)\\
&=\exists(country, genre)(\Longunderstack[l]{
\varphi\,'_1(cd, member, band)\wedge\\
\varphi\,'_2(cd,member, date)\wedge\\
\varphi\,'_3(cd, member,country))
}
\end{align*}

We now want to prove that similarity conditions hold for these three functions we defined.\\

\end{document} 