VR and density
I'm currently reading Aircraft Performance, written by P.J. Swatton, and I got a bit confused regarding the rotation speed (VR) and how it is affected by density altitude. My understanding is that since VR is an indicated airspeed, an aircraft should lift off at the same indicated airspeed, with both low and high density.
However, in the book it is stated that if the density is decreased, VR will increase to produce enough lift required for lift off.
This statement will be true if we are talking about TAS, but is the same true for IAS?