Input: Article: DC commutating electric motors, if fitted with laminated pole pieces, become universal motors because they can also operate on AC; reversing the current in both stator and rotor does not reverse the motor. But the now-standard AC distribution frequencies of 50 and 60 Hz caused difficulties with inductive reactance and eddy current losses. Many railways chose low AC frequencies to overcome these problems. They must be converted from utility power by motor-generators or static inverters at the feeding substations or generated at dedicated traction powerstations.

Now answer this question: How do railways try to solve the problem of inductive reactance of AC system?

Output: low AC frequencies

Input: Article: The first Industrial Revolution merged into the Second Industrial Revolution around 1850, when technological and economic progress gained momentum with the development of steam-powered ships and railways, and later in the 19th century with the internal combustion engine and electric power generation. The Second Industrial Revolution was a phase of the Industrial Revolution; labeled as the separate Technical Revolution. From a technological and a social point of view there is no clean break between the two. Major innovations during the period occurred in the chemical, electrical, petroleum, and steel industries. Specific advancements included the introduction of oil fired steam turbine and internal combustion driven steel ships, the development of the airplane, the practical commercialization of the automobile, mass production of consumer goods, the perfection of canning, mechanical refrigeration and other food preservation techniques, and the invention of the telephone.

Now answer this question: What was the second industrial revolution was labeled?

Output: separate Technical Revolution

Input: Article: Generally, post-punk music is defined as music that emerged from the cultural milieu of punk rock in the late 1970s, although many groups now categorized as post-punk were initially subsumed under the broad umbrella of punk or new wave music, only becoming differentiated as the terms came to signify more narrow styles. Additionally, the accuracy of the term's chronological prefix "post" has been disputed, as various groups commonly labeled post-punk in fact predate the punk rock movement. Reynolds defined the post-punk era as occurring loosely between 1978 and 1984.

Now answer this question: Why has the prefix 'post' caused a bit of dispute as it relates to various post-punk groups?

Output:
predate the punk rock movement