semivariance vs downside deviation

CFA Level III
#1

schweser book 2 page 185 defines semivariance as bottom half of the variane, or variances calculated using only the returns below the expected return. so is this the same thing as downside deviation?

i figure target semivariance is different/lower because you are using a lower target minimum such as zero, so target semivariance < semivariance…but semivariance = downside deviatiion?

#2

I believe the squareroot of the semi varience = downside deviation

#3

I believe the squareroot of the semi varience = downside deviation

#4

oh that makes sense

square root of variance = standard deviation

square root of semivariance = downside deviation