The Professor stared at the board.
The Black woman stopped.
Looked toward the candidate.
Then smiled for the first time.
"Exactly."
The Professor moved closer.
His eyes scanned the equations.
"No."
He grabbed another piece of chalk.
"This step."
He pointed.
"You cannot assume boundedness here."
"I didn't."
"You did."
She tapped the previous line.
"I proved local boundedness under the reduced measure."
"That does not imply—"
"Read the next line."
He did.
Silence.
Several seconds.
The Professor's face flushed.
The Black woman waited.
He finally said:
"Continue."
She did.
Twenty minutes after touching the chalk, she reached the last third of the proof.
Now even students standing against the walls had moved forward.
Nobody wanted to miss anything.
The Professor no longer joked.
The Black woman wrote faster.
The proof seemed less like something she was discovering than something she remembered.
That bothered one student enough to say it aloud.
"You've seen this before."
The woman stopped.
The Professor's eyes snapped toward her.
The student clarified:
"I mean—not as an insult."
"You're writing like you've done it before."
The Black woman slowly placed the chalk against the tray.
The Professor folded his arms.
"Good observation."
He looked toward her.
"Have you?"
She stared at the board.
Then answered:
"Yes."
The hall erupted in murmurs.
The Professor smiled immediately.
"There we are."
He turned toward the students.
"Which, unfortunately, invalidates the challenge."
The Black woman looked toward him.
"Why?"
"Because this is supposed to test your ability to derive the proof."
"Not repeat something you've memorized."
She stared.
"That's not what the board says."
Laughter.
Real laughter this time.
The Professor's smile vanished.