go upstream

1. Origins, structure, and basic meaning

• Structure: The on reading is そ, and the kun reading is さかのぼる. It has 14 strokes and relates to tracing back into the past or applying a rule retroactively.
• Basic usage: 遡る is read さかのぼる, and 遡及 is read そきゅう.

2. Common pitfalls and similar expressions

• 遡る / 遡及
  • 遡る means go back or trace back and is read さかのぼる. It describes tracing a family tree or records back to an earlier point.
  • 家系図を三代前まで遡って調べた。 means “I traced my family tree back three generations.”
  • 遡及 means retroactive application or retroactivity and is read そきゅう. It refers to applying a rule or system retroactively.
  • 授業では、規則の遡及をめぐる架空の事例を検討した。 means “In class, we considered a fictional case involving the retroactive application of rules.”