Consider a spreadsheet containing a set of cells C. A cell c can contain a formula that depends on zero or more other cells. Write  to denote the relation {hp,si : cell s depends on cell p}. For...

Consider a spreadsheet containing a set of cells C. A cell c can contain a formula that depends on zero or more other cells. Write  to denote the relation {hp,si : cell s depends on cell p}. For example, the value of cell C2 might be the result of the formula A2 ∗ B1; here A2  C2 and B1  C2. A spreadsheet is only meaningful if  is a strict partial order. Give a description (in English) of what it means for a cell c to be a minimal element under , and what it means for a cell c ′ to be a maximal element under .