Part: Part Ten - Adjusting to Different Stacks

Isolate the short stack

Pre-flop
Blinds 400 / 800 (100 ante)Pot 7,100 (8.9 BB)You: big stack • isolate the shortCOA♠Q♠● 60,000 (75 BB)YOUto actMP● 5,000 (6.2 BB)Short stackall-in 5,000 (6.2 BB)BTN● 18,000 (22.5 BB)Mediumyet to actSB● 60,000 (75 BB)posts 400 (0.5 BB)BB● 60,000 (75 BB)posts 800 (1 BB)D

A short stack open-jams. You're the big stack with A♠Q♠, and a medium stack is still to act behind you.

A short jams; you hold A♠Q♠ with a medium stack yet to act. Best?

WhyRe-raise to isolate. Just calling invites the medium stack behind to come along and could put your equity into a multiway pot; re-jamming folds him out and gets you heads-up against the short stack with your strong hand. With a big stack and A-Q, isolate.
What happensYou re-jam; the medium folds and you're heads-up versus the short.  Isolation complete.
With a strong hand and players left behind, you re-raised to isolate the all-in short stack - protecting your equity by denying the medium stack a cheap entry.

Re-raise to isolate a short stack's all-in when players remain behind - get heads-up with your strong hand instead of risking a multiway pot.