riguroso in English:

stringent guidelines

The law concerning drug trafficking is very stringent.

Confidence intervals with stringent significance levels

The most stringent protection of free speech would not protect a man in falsely shouting fire in a theatre and causing a panic.

The argument is rigorous and coherent but ultimately unconvincing.

Our plan has to be rigorous in order to be successful.

rigorous ​testing/​checking/​methods

Definition if something is rigorous, it is careful and thorough

a rigorous analysis of defence needs

rigorous calculations

When a phone arrives at a recycling centre it goes through a rigorous testing process.

The top engineer put the car through a series of rigorous tests.

The thief or swindler who has gained great wealth by his delinquency has a better chance than the small thief of escaping the rigorous penalty of the law.