Mathematical Annotation in R

In R, I can create text label "0 <= x" on my graph by saying

text(0, 0, expression(italic(0 <= x开发者_StackOverflow中文版)));

Now, how can I create the label "0 <= x <= 1"?

I'm not sure if this is a formal way, but try this:

plot(0,0,col=0)
text(0, 0, expression(italic(0 <= {x <= 1})))