After a while.
Xin Ya received a call and spoke in English for a short while. Then, together with Dean Pan and Zhang Ye, they proceeded back to the office to receive about a dozen foreign guests.
A middle-aged Caucasian man looked at Zhang Ye and said, "Zhang?"
Xin Ya then introduced them in English, "This is Professor Zhang Ye."
The Caucasian man replied very passionately, "Zhang, I'm finally able to meet you in person!"
"Hello," Zhang Ye said not knowing who he was but shook his hands anyway.
At the other side, a man who looked like he was in his forties, and was probably English, walked up to them. He did not say anything except to ask directly about a question he had regarding Dale's Conjecture. It seemed like he was unsure about a formula used in the proof.
Xin Ya and Dean Pan both introduced Zhang Ye to him.
"This is Oxford's Doctor Firth."
"This is Cambridge's Professor Baker."
This is Professor Kato from Tokyo University."
"This is…"