TASK DEFINITION: In this task, you're given a sentence and your task is to generate a simplified sentence that focuses on lexical paraphrasing from the original sentence given in the input.
PROBLEM: construction was completed in 1254 under frederick 's son , conrad iv of germany.

SOLUTION: construction was finished in 1254 under frederick 's son , conrad iv of germany.

PROBLEM: a material such as gold , which is chemically inert at normal scales , can serve as a potent chemical catalyst at nanoscales.

SOLUTION: gold does n't react with other chemicals unless it is used in very , very tiny amounts.

PROBLEM: while the weight of matter is entirely dependent upon the strength of gravity , the mass of matter is invariant.

SOLUTION:
the mass of the matter does not change even though the weight changes depending on gravity.