File talk:Permanent-Nonneg2Powers.png

The sum of powers of 2 looks as if it was coded in LaTeX as

2^{x_1} + 2^{x_2} + ... + 2^{x_r}

rather than as

2^{x_1} + 2^{x_2} + \ldots + 2^{x_r}

or

2^{x_1} + 2^{x_2} + \cdots + 2^{x_r}.

The spacing between the dots is smaller than standard spacing that would result from \cdots or \ldots. I would use \cdots for this (and \ldots if it were between commas rather than between plus signs. Michael Hardy (talk) 13:19, 15 December 2014 (UTC)