Q: What is a question about this article? If the question is unanswerable, say "unanswerable".
In the medieval period the wall circuit was expanded. Via Vittorio Emanuele continued to be the main road east-west through the walled city. West gate was still Porta Nuova, the circuit continued to Corso Alberti, to Piazza Vittorio Emanuele Orlando where it turned east along Via Volturno to Piazza Verdi and along the line of Via Cavour. At this north-east corner there was a defence, Castello a Mare, to protect the port at La Cala. A huge chain was used to block La Cala with the other end at S Maria della Catena (St Mary of the Chain). The sea-side wall was along the western side of Foro Italico Umberto. The wall turns west along the northern side of Via Abramo Lincoln, continues along Corso Tukory. The wall turns north approximately on Via Benedetto, to Palazzo dei Normanni and back to Porta Nuova. Source: Palermo - City Guide by Adriana Chirco, 1998, Dario Flaccovio Editore.
What used to block the West gate?
A: unanswerable

Q: What is a question about this article? If the question is unanswerable, say "unanswerable".
In mathematics, a group is an algebraic structure consisting of a set of elements equipped with an operation that combines any two elements to form a third element. The operation satisfies four conditions called the group axioms, namely closure, associativity, identity and invertibility. One of the most familiar examples of a group is the set of integers together with the addition operation, but the abstract formalization of the group axioms, detached as it is from the concrete nature of any particular group and its operation, applies much more widely. It allows entities with highly diverse mathematical origins in abstract algebra and beyond to be handled in a flexible way while retaining their essential structural aspects. The ubiquity of groups in numerous areas within and outside mathematics makes them a central organizing principle of contemporary mathematics.
What is the abstract formalization attached to?
A: unanswerable

Q: What is a question about this article? If the question is unanswerable, say "unanswerable".
The modern concept of an abstract group developed out of several fields of mathematics. The original motivation for group theory was the quest for solutions of polynomial equations of degree higher than 4. The 19th-century French mathematician Evariste Galois, extending prior work of Paolo Ruffini and Joseph-Louis Lagrange, gave a criterion for the solvability of a particular polynomial equation in terms of the symmetry group of its roots (solutions). The elements of such a Galois group correspond to certain permutations of the roots. At first, Galois' ideas were rejected by his contemporaries, and published only posthumously. More general permutation groups were investigated in particular by Augustin Louis Cauchy. Arthur Cayley's On the theory of groups, as depending on the symbolic equation n = 1 (1854) gives the first abstract definition of a finite group.
People were looking for polynomial equations under what number?
A: unanswerable

Q: What is a question about this article? If the question is unanswerable, say "unanswerable".
In classical physics, an inertial reference frame is one in which an object that experiences no forces does not accelerate. In general relativity, an inertial frame of reference is one that is following a geodesic of space-time. An object that moves against a geodesic experiences a force. An object in free fall does not experience a force, because it is following a geodesic. An object standing on the earth, however, will experience a force, as it is being held against the geodesic by the surface of the planet. In light of this, the bucket of water rotating in empty space will experience a force because it rotates with respect to the geodesic. The water will become concave, not because it is rotating with respect to the distant stars, but because it is rotating with respect to the geodesic.
What is experienced by objects in free-fall?
A:
unanswerable