[Tex/LaTex] Argument in Discrete Mathematics

Question

This is my code:

\begin{tabular}{cccc}
$P(1)$ \\
$P(1)$ \\
$\forall n \in \N ((P(n) \land P(n+1) \implies P(n+2))$ \\
\hline
$\forall n \in \N (P(n))$ \\
\end{tabular} 

It looks like this:

I want it to look like this:

So my question really is, how can I align each line to the left within the tabular. Alternatively, is there a package just for this? Thanks in advance.

Answer 1

Alternatively, is there a package just for this?

Yes, I believe ebproof really fits the bill.

\documentclass{article}
\usepackage{ebproof}
\usepackage{mathtools}
\usepackage{amssymb}
\begin{document}
\begin{prooftree}
    \hypo{&P(1)}
    \infer[no rule]1{&P(2)}
    \infer[no rule]1{&\forall n \in \mathbf{N} ((P(n) \land P(n+1) \implies P(n+2))}
    \infer1{& \therefore \forall n \in \mathbf{N} (P(n))}
\end{prooftree}
\end{document}

The & character is here to tune the alignment, there is no need to explicitly declare the math. environment, and the package is flexible enough to accommodate multiple variations.

As a side note, you can get the therefore symbol using other techniques.