In order to study classical physics rigorously and methodically, we need to classify systems. Historians disagree on how rigorously these laws were enforced. Fluoride toothpaste is the most widely used and rigorously evaluated fluoride treatment. Because these are so rigorously quantified, they are particularly important. Jockey weights began to be measured and rigorously enforced. Aspartame is one of the most rigorously tested food ingredients. He proceeded to rigorously deduce other properties by mathematical reasoning. At the moment only rigorously tested humans have experienced the conditions of space. Other participants were similarly prepared, though not as rigorously. Research indicates that measures must be applied rigorously and immediately in order to be effective. The law is different; it is rigorously standardised. He designs crafted bridal wear and rigorously structured pieces. However, there is little evidence to indicate that such tests are applied rigorously. Some countries like Ireland do not comply with the convention as rigorously as others. Instead, geneticists use concepts such as ancestry, which is more rigorously defined.