Operating Systems. The logic required to do operating systems/coding in general is exquisite, far beyond "an apple is an apple". That's trivial. A modern operating system is 10 million lines of code. Inherently, when something is fixed, something else is broken, keeping all that logic together.
Some other examples:
The first space shuttle flight was cancelled 20 minutes before its initial launch. This was done through the on-board computers. There were four on-board computers in redundancy which used an operating system called PASS. As a safety check, there was a fifth, completely independent and designed by an entirely different team. It used an operating system called BFS. On the first launch all four PASS computers voted go. The vote needed to be unanimous for launch. The BFS computer voted no. There was nothing wrong with the shuttle and the flight would have been a success. Upon investigation, engineers discovered a unique example of a classic OS design flaw in the logic of what OS engineers call "synchronization". How do I get the simplest of systems with two users to operate using shared memory space, which is often necessary, and sometimes useful, to cooperate and function properly to get the result I truly want and NOT the result I THINK the code is going to give me. Obviously, a computer, being truly, truly, truly, deeply stupid, will only do what you tell it to do. If it doesn't, it's your fault, and not the computer, always. NO matter how hard you try to convince yourself it's the computer's. The issue with BFS was indeterministic, which means it doesn't happen every time, which are the MOST FUN ones!!!! Some of these logic problems are impossible to diagnose without being used in production. Impossible. Such was the case of BFS. It happened only 1/67 times.
The Mars Rover experienced a "priority inversion issue", which caused it to reboot with frequency:
Mars Climate Orbiter, programming Imperial vs Metric units
CIO, Marie Mouchet
Bachelor of Arts and Master of Education degrees in Mathematics from Georgia State University.
CIO, Beth Jacob
BS, Retail Management, University of Minnesota
MBA, Organizational Leadership, University of Minnesota
CISO, Susan Mauldin
BA/MA Music Composition, University of Georgia
CIO, Matt Carey
Associate’s degree in information systems from Oklahoma State University – Okmulgee.
CIO, Bruce Hoffmeister
AS, Computer Science, BS, Mathematics/Biology, Thomas More University
MBA, Finance, Vanderbilt University