# Why is holomorphic = left moving?

1. Oct 10, 2014

### maverick280857

Hi,

Why does "holomorphic" have to be identified with "left-moving" (and not right-moving) in Polchinski's book, in chapter 2 (page 34)? The way I see it, a function of $\sigma^0-\sigma^1$ is like a function of $x-vt$ so it should be "right moving". Am I missing something here?

Thanks!

2. Oct 12, 2014

### torquil

That statement is made in eq. 2.1.13, and he comments on it in the sentence that follows. It is just a convention, and depends on how you choose to define the direction of increasing values in the coordinate system. If the direction of increasing values is towards the left, then the terminology makes sense.