I am trying to switch to Houdini from XSI.

In XSI I could do something called *symmetric modeling*. Cut an object by half, and mirror it. And edit just the source half, then I get exactly same result on both sides automatically mirrored without any concern.

I tried to do this with Modify - Mirror, but it seems the mirrored object is disconnected from source object, so editing on source object won't be applied on the mirrored object automatically.

How can I make it to be applied automatically?

See here. Full tutorial.

http://vimeo.com/34300829 [vimeo.com]