Ex10 13

$\def\abs#1{|#1|}\def\i{\mathbf {i}}\def\ket#1{|{#1}\rangle}\def\bra#1{\langle{#1}|}\def\braket#1#2{\langle{#1}|{#2}\rangle}\def\tr{\mathord{\mbox{tr}}}\mathbf{Exercise\ 10.13}$

Claim: LOCC cannot convert an unentangled state to an entangled one.

a) State the claim in more precise language.

b) Prove the claim.