Context and question: There are occasional brief hints and allusions in his longer works however that Avicenna considered philosophy as the only sensible way to distinguish real prophecy from illusion. He did not state this more clearly because of the political implications of such a theory, if prophecy could be questioned, and also because most of the time he was writing shorter works which concentrated on explaining his theories on philosophy and theology clearly, without digressing to consider epistemological matters which could only be properly considered by other philosophers.
What did Avicenna consider an illusion?
Answer: unanswerable
Context and question: In the classical case, the invariance, or symmetry, group and the covariance group coincide, but, interestingly enough, they part ways in relativistic physics. The symmetry group of the general theory of relativity includes all differentiable transformations, i.e., all properties of an object are dynamical, in other words there are no absolute objects. The formulations of the general theory of relativity, unlike those of classical mechanics, do not share a standard, i.e., there is no single formulation paired with transformations. As such the covariance group of the general theory of relativity is just the covariance group of every theory.
What else besides invariance, or symmetry and group part ways in relativistic physics?
Answer: the covariance group
Context and question: Despite early victories, Pyrrhus found his position in Italy untenable. Rome steadfastly refused to negotiate with Pyrrhus as long as his army remained in Italy. Facing unacceptably heavy losses from each encounter with the Roman army, Pyrrhus withdrew from the peninsula (hence the term "Pyrrhic victory"). In 275 BC, Pyrrhus again met the Roman army at the Battle of Beneventum. While Beneventum was indecisive, Pyrrhus realised his army had been exhausted and reduced by years of foreign campaigns. Seeing little hope for further gains, he withdrew completely from Italy.
What did Rome refuse to do in their relations with Pyrrhus?
Answer:
negotiate