If we can change a variable value such that the failure goes away, we do have a failure cause.

This minimal subset then at the given location is the variable that causes the failure.

Here's a quiz. I invoke the GNU compiler, and it crashes.

On the more philosophical level, when delta debugging returns, is not only to simply itself but is also to cause for the failure.

We can have errors that are not causes and causes that are not errors.

Reason unknown

So all of this looks very simple, however, in real life, it's much more complicated than that.

Note, like real infections, they can die out before they ever, ever cause real harm.

Again, we can use delta debugging to simplify this.

Be careful when you heard the word theory. Its meaning depends very much on whoever says it.

What we get in here is actually an entire cause effect chain.

Here's one, here's one, and there's one and you fix them and you think you're done, but you don't know whether any of these actually fixes the problem because it may well be that these errors you find that none of them actually causes the failure.

Cause of the explosion unconfirmed.

All you can tell is, there's a lot of swelling bronchiolitis.

We don't know why.

The cause of the accident is unknown.

The cause of the fire was unknown.

Cause of death remains unknown.

Which of the following is not true every infection can be traced back to a defect that causes it, every execution of a defect causes an infection, every infection ends in a failure, and finally, every defect can cause a failure up to you.

Computer glitch.

What's happened to us? A malfunction of some sort.

It appears it was merely a glitch in our system... an overlay of old code from our language training program... used to learn the English language.

The cause of the fire is not known.

The cause of the fire isn't known.

And no idea what caused it?

It is also unstable.

As of right now, we really can't say.

It is important to show both the defect is an error and the cause in order to avoid situations in which a defect only is an error but does not cause the failure or that something causes the failure but is not an error.

They are judge and defendant, they are professional politicians.

Finally, we need to make sure that quotes only have a special meaning within tags, so we make this endtag instead.

Too many factors. It's not that!

So, these genes are indeed going back to the populations.

Is there something wrong?

Now sleep...

The accident was due to his carelessness.

Cause?

In reality, we have 10,000 of such variables and not only do we have 10,000 of such variables, we also have 10,000 of steps between defect and failure.

In some places, that's part of it.

At present, the cause of the disease is unknown.

I think I found... I could be wrong.

You can execute a program again and again, never have a failure and still have a defect in there, however, if a program fails, that is if we actually see a failure, then we can always trace it back to the defect that causes it.

We're going to look at all the various input sources for your program and discuss how to capture and replay them such that you can faithfully reproduce a failure that happens in the field.

The cause of the fire was his cigarette butt.

Careless driving causes accidents.

The cause of the accident is not known to us.