Imaginary Numbers are not Imaginary Imaginary Numbers were once thought to be impossible, and so they were called Imaginary (to make fun of them). But then people researched them more and discovered they were actually useful and important because they filled a gap in mathematics ... but the imaginary name has stuck. And that is also how the name Real Numbers came about (real is not imaginary). Imaginary Numbers are Useful . Complex Numbers
Whether your spouse inherits your entire estate depends on your state's laws. If you die without a will, your estate is divided according to state intestacy laws. If you had a will, your spouse's share is partly dependent on what you left her and whether you have surviving children or parents.
Because the surviving spouse does not own the property, it is not subject to estate tax. Setting up an AB trust this way keeps the portion of the surviving spouse's estate that is taxable half of what it would be without an AB trust. Imagine a joint trust with $4,000,000 in assets. Husband dies leaving all of the trust property to Wife. Because transfers between spouses are not subject to estate tax, Wife will get the full $4,000,000, tax free.