The blood types we usually talk about are determined by the presence or absence of three antigens (A, B, and Rh-D). Here’s a table, where presence of an antigen is denoted by a 1 (true) and absence, by a 0 (false).

You will reject a blood donation if it contains an antigen that your own blood does not. This is why O- is the “universal donor” (none of those antigens to reject) and AB+ is the “universal recipient” (you have them all naturally, so nothing is rejected). Let’s make a truth table for this, just for the A antigen:

Does that look familiar? It should; it’s the logical implication operation. So a person can receive another’s blood if the donor’s blood type bitwise implies the recipient’s blood type. Neat.