The phrase "the theory asserts" is correct and usable in written English.
You can use the phrase when referring to a theory or idea that's being presented. For example, "The theory asserts that early exposure to foreign language can lead to increased fluency."
The theory asserts that, at the beginning of the time interval, all the nuclei are in an identical state and that the decay is a completely random process.
If the value obtained is, say, a5, the theory asserts that after the measurement the state of the system is no longer the original Ψ but has changed to ψ5, the state corresponding to a5.
Failure to find the cause the theory asserts to be there will in general not require the rejection of the theory: the claim is an existence claim, and a failure to find something asserted to exist does not refute that claim; perhaps one has not looked hard enough.
The following feature seems to be of interest: The concept of the determination of morphisms by modules concerns the category of maps with fixed target Y, namely one wants to decide whether two elements in [ → Y 〉 are comparable. The theory asserts that there is a test set of modules, namely the indecomposable direct summands of C ( f ).
The theory asserts that what is moral is determined by what God commands, and that to be moral is to follow his commands.
The theory asserts that good actions are morally good as a result of their being commanded by God, and many religious believers subscribe to some form of divine command theory.
Contemporary versions of the theory assert that knowing is a member of a group of mental states that can be arranged in a series according to increasing certitude.
Stronger versions of the theory assert that God's command is the only reason that a good action is moral, while weaker variations cast divine command as a vital component within a greater reason.
The theories asserted that Mr. Obama was born in Kenya, and is therefore not eligible to be president.
There is no reason to subscribe to any of the theories asserting that simply because, in the past, profit recessions have been followed by economic recessions, that must necessarily be true this time.
The hormonal theory asserts that the metabolism of caffeine and other coffee compounds interact mainly with the metabolism of estrogens.
