When cutting recipe for bagels in half,should the yeast amt. he halved alco. Using 2c. Flour instead of 4

Thank you so much for your answer. I am going to cut all the ingredients in half and see how it works out. I'll let you know!

Marilyn - when cutting a bread recipe in half, I generally divide each measurement in 2.
But with yeast, often a small amount to start with, you could keep the original measure. If you do, keep the original measures for proofing (warm water, maybe sugar). Also, expect the dough to rise a bit faster than normal because you're using more than normal amount of yeast.
Or, you could cut all the proofing ingredients (yeast, water, maybe sugar) in half and expect the same time lapses for raising the dough.