Question 3*+For a table with headings \(e,a\), the row \(e\) reads \(e,a\). What does this show about left multiplication by \(e\)?
Question 4*+If the entry in row \(a\), column \(b\) is \(e\), what inverse information does this provide?
Question 7**+A table has headings \(e,a,b\). The row \(e\) is \(e,a,b\), but the column \(e\) is \(e,b,a\). Can \(e\) be a two-sided identity?
Question 8**+In a table for \(G=\{e,a,b\}\), row \(a\), column \(b\) is \(e\), and row \(b\), column \(a\) is \(e\). What can you conclude?
Question 13****Build the Cayley table for \(\{0,1,2\}\) under addition modulo \(3\). Give the rows in order \(0,1,2\).
Question 15****+A table is symmetric across its main diagonal. What does that suggest about commutativity, and what does it not prove?
Question 16****+A finite table has every row and column containing each element exactly once. Why is this still not a complete proof that the table defines a group?
Question 18*****A student identifies an identity by finding only a row that reproduces the headings. Diagnose the mistake.
Question 19*****Prove that each column of a finite group table contains every group element exactly once.
Question 20*****A proposed table for four elements has one entry outside the listed set but otherwise looks like a group table. What is the decisive failure?