Deplorable Word word itself, and had vowed that none of them, nor their descendants, would seek to discover it. Jadis said she had "learned it in a secret place and paid a terrible price to learn it". The book does not say what that price was, or give further details on the Deplorable Word. Lewis does not explicitly link the Deplorable Word to any specific weapon of mass destruction, but he alludes to the power of humanity to destroy life. Writing in 1955 in the midst of the Cold War, Lewis has the lion Aslan say to the central characters from the
Word problem for groups would expect it to be difficult to prove as the mapping from presentations to simple groups would have to be non-recursive. The following has been proved by Bernhard Neumann and Angus Macintyre: What is remarkable about this is that the algebraically closed groups are so wild that none of them has a recursive presentation. The oldest result relating algebraic structure to solvability of the word problem is Kuznetsov's theorem: To prove this let ⟨"X"|"R"⟩ be a recursive presentation for "S". Choose "a" ∈ S such that "a" ≠ 1 in "S". If "w" is a word on the generators "X"