‘Ghost’ tones

1.
trigger tone change before disappearing
lǎohǔ            -->láohǔ                --> láohu
xiǎojiě          --> xiáojiě              --> xiáojie
liǎngběn       --> liángběn --> liángben
yìgè             --> yígè                 --> yíge
bùshì                     --> búshì               --> búshi

2. disappear before triggering tone change
jiějiě             --> jiějie
lǎozǐ            --> lǎozi (yours truly)
vs. lǎozǐ       --> láozǐ (Laotze, the Daoist philosopher)
 
3. resurfaced tones (with or without tone change)
xiǎojiě                   --> xiáojie              --> lǎo xiáojiě
xué+shēng             --> xuésheng         --> liúxuéshēng