I am working on Zweibach's First Course in String Theory and question 2.4 asks: Show that there are two points on the circle that are left fixed by the(adsbygoogle = window.adsbygoogle || []).push({}); Z2 action. (For those without the text, the circle is the space -1 < x <= +1, identified by x ~ x + 2. And theZ2 mod imposes the x ~ -x identification on the circle.)

I know that x = 0 is one of the fixed points, but the other alludes me. Just a guess, is it the center??? but that isnotin the fundamental domain!

...eek!

Thanks in advance,

-LD

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# How many fixed points on a circle S/Z2?

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