Editing Use-define chain (section)

==Setup==

The list of statements determines a strong order among statements. 
*Statements are labeled using the following conventions: {{tmath|s(i)}}, where ''i'' is an integer in {{tmath|[1,n]}}; and ''n'' is the number of statements in the [[basic block]]
*Variables are identified in italic (e.g., ''v'',''u'' and ''t'')
*Every variable is assumed to have a definition in the context or scope. (In [[static single assignment]] form, use-define chains are explicit because each chain contains a single element.)
For a variable, such as ''v'', its declaration is identified as ''V'' (italic capital letter), and for short, its declaration is identified as {{tmath|s(0)}}. In general, a declaration of a variable can be in an outer scope (e.g., a [[global variable]]).

===Definition of a variable===

When a variable, ''v'', is on the [[Left-hand side and right-hand side of an equation|LHS]] of an assignment statement, such as {{tmath|s(j)}}, then {{tmath|s(j)}} is a definition of ''v''. Every variable (''v'') has at least one definition by its declaration (''V'') (or initialization).

===Use of a variable===

If variable, ''v'', is on the RHS of statement {{tmath|s(j)}}, there is a statement, {{tmath|s(i)}} with ''i'' &lt; ''j'' and {{tmath|\min(j-i)}}, that it is a definition of ''v'' and it has a use at {{tmath|s(j)}} (or, in short, when a variable, ''v'', is on the RHS of a statement {{tmath|s(j)}}, then ''v'' has a use at statement {{tmath|s(j)}}).