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    rc45170a r08061589  
    1010%% Author           : Peter A. Buhr
    1111%% Created On       : Wed Apr  6 14:53:29 2016
    12 %% Last Modified By : Peter A. Buhr
    13 %% Last Modified On : Mon Aug  1 08:43:49 2016
    14 %% Update Count     : 1270
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     13%% Last Modified On : Sun Jul 31 07:27:55 2016
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    1515%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
    1616
     
    211211however, it largely extended the language, and did not address many existing problems.\footnote{%
    212212Two important existing problems addressed were changing the type of character literals from ©int© to ©char© and enumerator from ©int© to the type of its enumerators.}
    213 \Index*{Fortran}~\cite{Fortran08}, \Index*{Ada}~\cite{Ada12}, and \Index*{Cobol}~\cite{Cobol14} are examples of programming languages that took an evolutionary approach, where modern language features (\eg objects, concurrency) are added and problems fixed within the framework of the existing language.
     213\Index*{Fortran}~\cite{Fortran08}, \Index*{Ada}~\cite{Ada12}, and \Index*{Cobol}~\cite{Cobol14} are examples of programming languages that took an evolutionary approach, where modern language features (e.g., objects, concurrency) are added and problems fixed within the framework of the existing language.
    214214\Index*{Java}~\cite{Java8}, \Index*{Go}~\cite{Go}, \Index*{Rust}~\cite{Rust} and \Index*{D}~\cite{D} are examples of the revolutionary approach for modernizing C/\CC, resulting in a new language rather than an extension of the descendent.
    215215These languages have different syntax and semantics from C, and do not interoperate directly with C, largely because of garbage collection.
     
    265265\section[Compiling CFA Program]{Compiling \CFA Program}
    266266
    267 The command ©cfa© is used to compile \CFA program(s), and is based on the GNU \Indexc{gcc} command, \eg:
     267The command ©cfa© is used to compile \CFA program(s), and is based on the GNU \Indexc{gcc} command, e.g.:
    268268\begin{lstlisting}
    269269cfa§\indexc{cfa}\index{compilation!cfa@©cfa©}§ [ gcc-options ] C/§\CFA§-files [ assembler/loader-files ]
     
    350350\section{Underscores in Constants}
    351351
    352 Numeric constants are extended to allow \Index{underscore}s within constants\index{constant!underscore}, \eg:
     352Numeric constants are extended to allow \Index{underscore}s within constants\index{constant!underscore}, e.g.:
    353353\begin{lstlisting}
    3543542®_®147®_®483®_®648;                    §\C{// decimal constant}§
     
    366366\begin{enumerate}
    367367\item
    368 A sequence of underscores is disallowed, \eg ©12__34© is invalid.
     368A sequence of underscores is disallowed, e.g., ©12__34© is invalid.
    369369\item
    370370Underscores may only appear within a sequence of digits (regardless of the digit radix).
    371 In other words, an underscore cannot start or end a sequence of digits, \eg ©_1©, ©1_© and ©_1_© are invalid (actually, the 1st and 3rd examples are identifier names).
     371In other words, an underscore cannot start or end a sequence of digits, e.g., ©_1©, ©1_© and ©_1_© are invalid (actually, the 1st and 3rd examples are identifier names).
    372372\item
    373373A numeric prefix may end with an underscore;
     
    498498\end{quote2}
    499499
    500 All type qualifiers, \eg ©const©, ©volatile©, etc., are used in the normal way with the new declarations and also appear left to right, \eg:
     500All type qualifiers, e.g., ©const©, ©volatile©, etc., are used in the normal way with the new declarations and also appear left to right, e.g.:
    501501\begin{quote2}
    502502\begin{tabular}{@{}l@{\hspace{1em}}l@{\hspace{1em}}l@{}}
     
    518518\end{tabular}
    519519\end{quote2}
    520 All declaration qualifiers, \eg ©extern©, ©static©, etc., are used in the normal way with the new declarations but can only appear at the start of a \CFA routine declaration,\footnote{\label{StorageClassSpecifier}
    521 The placement of a storage-class specifier other than at the beginning of the declaration specifiers in a declaration is an obsolescent feature.~\cite[\S~6.11.5(1)]{C11}} \eg:
     520All declaration qualifiers, e.g., ©extern©, ©static©, etc., are used in the normal way with the new declarations but can only appear at the start of a \CFA routine declaration,\footnote{\label{StorageClassSpecifier}
     521The placement of a storage-class specifier other than at the beginning of the declaration specifiers in a declaration is an obsolescent feature.~\cite[\S~6.11.5(1)]{C11}} e.g.:
    522522\begin{quote2}
    523523\begin{tabular}{@{}l@{\hspace{3em}}l@{\hspace{2em}}l@{}}
     
    542542Unsupported are K\&R C declarations where the base type defaults to ©int©, if no type is specified,\footnote{
    543543At least one type specifier shall be given in the declaration specifiers in each declaration, and in the specifier-qualifier list in each structure declaration and type name~\cite[\S~6.7.2(2)]{C11}}
    544 \eg:
     544e.g.:
    545545\begin{lstlisting}
    546546x;                                                              §\C{// int x}§
     
    612612A \Index{pointer}/\Index{reference} is a generalization of a variable name, i.e., a mutable address that can point to more than one memory location during its lifetime.
    613613(Similarly, an integer variable can contain multiple integer literals during its lifetime versus an integer constant representing a single literal during its lifetime and may not occupy storage as the literal is embedded directly into instructions.)
    614 Hence, a pointer occupies memory to store its current address, and the pointer's value is loaded by dereferencing, \eg:
     614Hence, a pointer occupies memory to store its current address, and the pointer's value is loaded by dereferencing, e.g.:
    615615\begin{quote2}
    616616\begin{tabular}{@{}ll@{}}
     
    669669Except for auto-dereferencing by the compiler, this reference example is the same as the previous pointer example.
    670670Hence, a reference behaves like the variable name for the current variable it is pointing-to.
    671 The simplest way to understand a reference is to imagine the compiler inserting a dereference operator before the reference variable for each reference qualifier in a declaration, \eg:
     671The simplest way to understand a reference is to imagine the compiler inserting a dereference operator before the reference variable for each reference qualifier in a declaration, e.g.:
    672672\begin{lstlisting}
    673673r2 = ((r1 + r2) * (r3 - r1)) / (r3 - 15);
     
    677677®*®r2 = ((®*®r1 + ®*®r2) ®*® (®**®r3 - ®*®r1)) / (®**®r3 - 15);
    678678\end{lstlisting}
    679 When a reference operation appears beside a dereference operation, \eg ©&*©, they cancel out.\footnote{
     679When a reference operation appears beside a dereference operation, e.g., ©&*©, they cancel out.\footnote{
    680680The unary ©&© operator yields the address of its operand.
    681681If the operand has type ``type'', the result has type ``pointer to type''.
     
    721721®&®crc = &cx;                                   §\C{// error, cannot change crc}§
    722722\end{lstlisting}
    723 Hence, for type ©& const©, there is no pointer assignment, so ©&rc = &x© is disallowed, and \emph{the address value cannot be ©0© unless an arbitrary pointer is assigned to the reference}, \eg:
     723Hence, for type ©& const©, there is no pointer assignment, so ©&rc = &x© is disallowed, and \emph{the address value cannot be ©0© unless an arbitrary pointer is assigned to the reference}, e.g.:
    724724\begin{lstlisting}
    725725int & const r = *0;                             §\C{// where 0 is the int * zero}§
    726726\end{lstlisting}
    727727Otherwise, the compiler is managing the addresses for type ©& const© not the programmer, and by a programming discipline of only using references with references, address errors can be prevented.
    728 Finally, the position of the ©const© qualifier \emph{after} the pointer/reference qualifier causes confuse for C programmers.
    729 The ©const© qualifier cannot be moved before the pointer/reference qualifier for C style-declarations;
    730 \CFA-style declarations attempt to address this issue:
    731 \begin{quote2}
    732 \begin{tabular}{@{}l@{\hspace{3em}}l@{}}
    733 \multicolumn{1}{c@{\hspace{3em}}}{\textbf{\CFA}}        & \multicolumn{1}{c}{\textbf{C}}        \\
    734 \begin{lstlisting}
    735 ®const® * ®const® * const int ccp;
    736 ®const® & ®const® & const int ccr;
    737 \end{lstlisting}
    738 &
    739 \begin{lstlisting}
    740 const int * ®const® * ®const® ccp;
    741 
    742 \end{lstlisting}
    743 \end{tabular}
    744 \end{quote2}
    745 where the \CFA declaration is read left-to-right (see \VRef{s:Declarations}).
    746728
    747729\Index{Initialization} is different than \Index{assignment} because initialization occurs on the empty (uninitialized) storage on an object, while assignment occurs on possibly initialized storage of an object.
     
    803785\section{Type Operators}
    804786
    805 The new declaration syntax can be used in other contexts where types are required, \eg casts and the pseudo-routine ©sizeof©:
     787The new declaration syntax can be used in other contexts where types are required, e.g., casts and the pseudo-routine ©sizeof©:
    806788\begin{quote2}
    807789\begin{tabular}{@{}l@{\hspace{3em}}l@{}}
     
    823805
    824806\CFA also supports a new syntax for routine definition, as well as ISO C and K\&R routine syntax.
    825 The point of the new syntax is to allow returning multiple values from a routine~\cite{Galletly96,CLU}, \eg:
     807The point of the new syntax is to allow returning multiple values from a routine~\cite{Galletly96,CLU}, e.g.:
    826808\begin{lstlisting}
    827809®[ int o1, int o2, char o3 ]® f( int i1, char i2, char i3 ) {
     
    835817\Index*{Michael Tiemann}, with help from \Index*{Doug Lea}, provided named return values in g++, circa 1989.}
    836818The value of each local return variable is automatically returned at routine termination.
    837 Declaration qualifiers can only appear at the start of a routine definition, \eg:
     819Declaration qualifiers can only appear at the start of a routine definition, e.g.:
    838820\begin{lstlisting}
    839821®extern® [ int x ] g( int y ) {§\,§}
     
    867849The inability to use \CFA declarations in these two contexts is probably a blessing because it precludes programmers from arbitrarily switching between declarations forms within a declaration contexts.
    868850
    869 C-style declarations can be used to declare parameters for \CFA style routine definitions, \eg:
     851C-style declarations can be used to declare parameters for \CFA style routine definitions, e.g.:
    870852\begin{lstlisting}
    871853[ int ] f( * int, int * );              §\C{// returns an integer, accepts 2 pointers to integers}§
     
    916898
    917899The syntax of the new routine prototype declaration follows directly from the new routine definition syntax;
    918 as well, parameter names are optional, \eg:
     900as well, parameter names are optional, e.g.:
    919901\begin{lstlisting}
    920902[ int x ] f ();                                 §\C{// returning int with no parameters}§
     
    924906\end{lstlisting}
    925907This syntax allows a prototype declaration to be created by cutting and pasting source text from the routine definition header (or vice versa).
    926 It is possible to declare multiple routine-prototypes in a single declaration, but the entire type specification is distributed across \emph{all} routine names in the declaration list (see~\VRef{s:Declarations}), \eg:
     908It is possible to declare multiple routine-prototypes in a single declaration, but the entire type specification is distributed across \emph{all} routine names in the declaration list (see~\VRef{s:Declarations}), e.g.:
    927909\begin{quote2}
    928910\begin{tabular}{@{}l@{\hspace{3em}}l@{}}
     
    937919\end{tabular}
    938920\end{quote2}
    939 Declaration qualifiers can only appear at the start of a \CFA routine declaration,\footref{StorageClassSpecifier} \eg:
     921Declaration qualifiers can only appear at the start of a \CFA routine declaration,\footref{StorageClassSpecifier} e.g.:
    940922\begin{lstlisting}
    941923extern [ int ] f (int);
     
    946928\section{Routine Pointers}
    947929
    948 The syntax for pointers to \CFA routines specifies the pointer name on the right, \eg:
     930The syntax for pointers to \CFA routines specifies the pointer name on the right, e.g.:
    949931\begin{lstlisting}
    950932* [ int x ] () fp;                      §\C{// pointer to routine returning int with no parameters}§
     
    10641046p( /* positional */, /* named */, . . . );
    10651047\end{lstlisting}
    1066 While it is possible to implement both approaches, the first possibly is more complex than the second, \eg:
     1048While it is possible to implement both approaches, the first possibly is more complex than the second, e.g.:
    10671049\begin{lstlisting}
    10681050p( int x, int y, int z, . . . );
     
    10741056In the second call, the named arguments separate the positional and ellipse arguments, making it trivial to read the call.
    10751057
    1076 The problem is exacerbated with default arguments, \eg:
     1058The problem is exacerbated with default arguments, e.g.:
    10771059\begin{lstlisting}
    10781060void p( int x, int y = 2, int z = 3. . . );
     
    12821264
    12831265As mentioned, tuples can appear in contexts requiring a list of value, such as an argument list of a routine call.
    1284 In unambiguous situations, the tuple brackets may be omitted, \eg a tuple that appears as an argument may have its
     1266In unambiguous situations, the tuple brackets may be omitted, e.g., a tuple that appears as an argument may have its
    12851267square brackets omitted for convenience; therefore, the following routine invocations are equivalent:
    12861268\begin{lstlisting}
     
    13211303
    13221304Type qualifiers, i.e., const and volatile, may modify a tuple type.
    1323 The meaning is the same as for a type qualifier modifying an aggregate type [Int99, x 6.5.2.3(7),x 6.7.3(11)], i.e., the qualifier is distributed across all of the types in the tuple, \eg:
     1305The meaning is the same as for a type qualifier modifying an aggregate type [Int99, x 6.5.2.3(7),x 6.7.3(11)], i.e., the qualifier is distributed across all of the types in the tuple, e.g.:
    13241306\begin{lstlisting}
    13251307const volatile [ int, float, const int ] x;
     
    13291311[ const volatile int, const volatile float, const volatile int ] x;
    13301312\end{lstlisting}
    1331 Declaration qualifiers can only appear at the start of a \CFA tuple declaration4, \eg:
     1313Declaration qualifiers can only appear at the start of a \CFA tuple declaration4, e.g.:
    13321314\begin{lstlisting}
    13331315extern [ int, int ] w1;
     
    13371319Unfortunately, C's syntax for subscripts precluded treating them as tuples.
    13381320The C subscript list has the form ©[i][j]...© and not ©[i, j, ...]©.
    1339 Therefore, there is no syntactic way for a routine returning multiple values to specify the different subscript values, \eg ©f[g()]© always means a single subscript value because there is only one set of brackets.
     1321Therefore, there is no syntactic way for a routine returning multiple values to specify the different subscript values, e.g., ©f[g()]© always means a single subscript value because there is only one set of brackets.
    13401322Fixing this requires a major change to C because the syntactic form ©M[i, j, k]© already has a particular meaning: ©i, j, k© is a comma expression.
    13411323\end{rationale}
     
    13981380Clearly, the types of the entities being assigned must be type compatible with the value of the expression.
    13991381
    1400 Mass assignment has parallel semantics, \eg the statement:
     1382Mass assignment has parallel semantics, e.g., the statement:
    14011383\begin{lstlisting}
    14021384[ x, y, z ] = 1.5;
     
    14871469\section{Unnamed Structure Fields}
    14881470
    1489 C requires each field of a structure to have a name, except for a bit field associated with a basic type, \eg:
     1471C requires each field of a structure to have a name, except for a bit field associated with a basic type, e.g.:
    14901472\begin{lstlisting}
    14911473struct {
    1492         int f1;                                 §\C{// named field}§
    1493         int f2 : 4;                             §\C{// named field with bit field size}§
    1494         int : 3;                                §\C{// unnamed field for basic type with bit field size}§
    1495         int ;                                   §\C{// disallowed, unnamed field}§
    1496         int *;                                  §\C{// disallowed, unnamed field}§
    1497         int (*)(int);                   §\C{// disallowed, unnamed field}§
     1474        int f1;                 // named field
     1475        int f2 : 4;             // named field with bit field size
     1476        int : 3;                // unnamed field for basic type with bit field size
     1477        int ;                   // disallowed, unnamed field
     1478        int *;                  // disallowed, unnamed field
     1479        int (*)(int);   // disallowed, unnamed field
    14981480};
    14991481\end{lstlisting}
    15001482This requirement is relaxed by making the field name optional for all field declarations; therefore, all the field declarations in the example are allowed.
    15011483As for unnamed bit fields, an unnamed field is used for padding a structure to a particular size.
    1502 A list of unnamed fields is also supported, \eg:
     1484A list of unnamed fields is also supported, e.g.:
    15031485\begin{lstlisting}
    15041486struct {
    1505         int , , ;                               §\C{// 3 unnamed fields}§
     1487        int , , ;               // 3 unnamed fields
    15061488}
    15071489\end{lstlisting}
     
    15161498§\emph{expr}§ -> [ §\emph{fieldlist}§ ]
    15171499\end{lstlisting}
    1518 \emph{expr} is any expression yielding a value of type record, \eg ©struct©, ©union©.
     1500\emph{expr} is any expression yielding a value of type record, e.g., ©struct©, ©union©.
    15191501Each element of \emph{ fieldlist} is an element of the record specified by \emph{expr}.
    15201502A record-field tuple may be used anywhere a tuple can be used. An example of the use of a record-field tuple is
     
    17781760}
    17791761\end{lstlisting}
    1780 While the declaration of the local variable ©y© is useful with a scope across all ©case© clauses, the initialization for such a variable is defined to never be executed because control always transfers over it.
    1781 Furthermore, any statements before the first ©case© clause can only be executed if labelled and transferred to using a ©goto©, either from outside or inside of the ©switch©, both of which are problematic.
    1782 As well, the declaration of ©z© cannot occur after the ©case© because a label can only be attached to a statement, and without a fall through to case 3, ©z© is uninitialized.
    1783 The key observation is that the ©switch© statement branches into control structure, i.e., there are multiple entry points into its statement body.
     1762While the declaration of the local variable ©y© is useful and its scope is across all ©case© clauses, the initialization for such a variable is defined to never be executed because control always transfers over it.
     1763Furthermore, any statements before the first ©case© clause can only be executed if labelled and transferred to using a ©goto©, either from outside or inside of the ©switch©.
     1764As mentioned, transfer into control structures should be forbidden;
     1765transfers from within the ©switch© body using a ©goto© are equally unpalatable.
     1766As well, the declaration of ©z© is cannot occur after the ©case© because a label can only be attached to a statement, and without a fall through to case 3, ©z© is uninitialized.
    17841767\end{enumerate}
    17851768
     
    17951778and there is only a medium amount of fall-through from one ©case© clause to the next, and most of these result from a list of case values executing common code, rather than a sequence of case actions that compound.
    17961779\end{itemize}
    1797 These observations help to put the suggested changes to the ©switch© into perspective.
     1780These observations help to put the \CFA changes to the ©switch© into perspective.
    17981781\begin{enumerate}
    17991782\item
    18001783Eliminating default fall-through has the greatest potential for affecting existing code.
    1801 However, even if fall-through is removed, most ©switch© statements would continue to work because of the explicit transfers already present at the end of each ©case© clause, the common placement of the ©default© clause at the end of the case list, and the most common use of fall-through, i.e., a list of ©case© clauses executing common code, \eg:
    1802  \begin{lstlisting}
     1784However, even if fall-through is removed, most ©switch© statements would continue to work because of the explicit transfers already present at the end of each ©case© clause, the common placement of the ©default© clause at the end of the case list, and the most common use of fall-through, i.e., a list of ©case© clauses executing common code, e.g.:
     1785\begin{lstlisting}
    18031786case 1:  case 2:  case 3: ...
    18041787\end{lstlisting}
    18051788still work.
    18061789Nevertheless, reversing the default action would have a non-trivial effect on case actions that compound, such as the above example of processing shell arguments.
    1807 Therefore, to preserve backwards compatibility, it is necessary to introduce a new kind of ©switch© statement, called ©choose©, with no implicit fall-through semantics and an explicit fall-through if the last statement of a case-clause ends with the new keyword ©fallthru©, \eg:
     1790Therefore, to preserve backwards compatibility, it is necessary to introduce a new kind of ©switch© statement, called ©choose©, with no implicit fall-through semantics and an explicit fall-through if the last statement of a case-clause ends with the new keyword ©fallthrough©/©fallthru©, e.g.:
    18081791\begin{lstlisting}
    18091792®choose® ( i ) {
     
    18321815Therefore, no change is made for this issue.
    18331816\item
    1834 Dealing with unreachable code in a ©switch©/©choose© body is solved by restricting declarations and associated initialization to the start of statement body, which is executed \emph{before} the transfer to the appropriate ©case© clause\footnote{
    1835 Essentially, these declarations are hoisted before the ©switch©/©choose© statement and both declarations and statement are surrounded by a compound statement.} and precluding statements before the first ©case© clause.
    1836 Further declarations at the same nesting level as the statement body are disallowed to ensure every transfer into the body is sound.
     1817Dealing with unreachable code in a ©switch©/©choose© body is solved by restricting declarations and associated initialization to the start of statement body, which is executed \emph{before} the transfer to the appropriate ©case© clause.\footnote{
     1818Essentially, these declarations are hoisted before the statement and both declarations and statement are surrounded by a compound statement.} and precluding statements before the first ©case© clause.
     1819Further declaration in the statement body are disallowed.
    18371820\begin{lstlisting}
    18381821switch ( x ) {
    1839         ®int i = 0;®                            §\C{// allowed only at start
     1822        ®int i = 0;®                            §\C{// allowed
    18401823  case 0:
    18411824        ...
    1842         ®int j = 0;®                            §\C{// disallowed}§
     1825        ®int i = 0;®                            §\C{// disallowed}§
    18431826  case 1:
    18441827    {
    1845                 ®int k = 0;®                    §\C{// allowed at different nesting levels
     1828                ®int i = 0;®                    §\C{// allowed in any compound statement
    18461829                ...
    18471830        }
     
    27242707Like the \Index*[C++]{\CC} lexical problem with closing template-syntax, e.g, ©Foo<Bar<int®>>®©, this issue can be solved with a more powerful lexer/parser.
    27252708
    2726 There are several ambiguous cases with operator identifiers, \eg ©int *?*?()©, where the string ©*?*?© can be lexed as ©*©/©?*?© or ©*?©/©*?©.
    2727 Since it is common practise to put a unary operator juxtaposed to an identifier, \eg ©*i©, users will be annoyed if they cannot do this with respect to operator identifiers.
     2709There are several ambiguous cases with operator identifiers, e.g., ©int *?*?()©, where the string ©*?*?© can be lexed as ©*©/©?*?© or ©*?©/©*?©.
     2710Since it is common practise to put a unary operator juxtaposed to an identifier, e.g., ©*i©, users will be annoyed if they cannot do this with respect to operator identifiers.
    27282711Even with this special hack, there are 5 general cases that cannot be handled.
    27292712The first case is for the function-call identifier ©?()©:
     
    27902773This means that a function requiring mutual exclusion could block if the lock is already held by another thread.
    27912774Blocking on a monitor lock does not block the kernel thread, it simply blocks the user thread, which yields its kernel thread while waiting to obtain the lock.
    2792 If multiple mutex parameters are specified, they will be locked in parameter order (\ie first parameter is locked first) and unlocked in the
     2775If multiple mutex parameters are specified, they will be locked in parameter order (i.e. first parameter is locked first) and unlocked in the
    27932776reverse order.
    27942777\begin{lstlisting}
     
    43594342
    43604343
     4344\section{New Keywowrds}
     4345
     4346©catch©, ©catchResume©, ©choose©, \quad ©disable©, ©dtype©, \quad ©enable©, \quad ©fallthrough©, ©fallthru©, ©finally©, ©forall©, ©ftype©, \quad ©lvalue©, \quad ©otype©, \quad ©throw©, ©throwResume©, ©trait©, ©try©
     4347
     4348
    43614349\section{Incompatible}
    43624350
     
    44884476\CFA is C \emph{incompatible} on this issue, and provides semantics similar to \Index*[C++]{\CC}.
    44894477Nested types are not hoisted and can be referenced using the field selection operator ``©.©'', unlike the \CC scope-resolution operator ``©::©''.
    4490 Given that nested types in C are equivalent to not using them, \ie they are essentially useless, it is unlikely there are any realistic usages that break because of this incompatibility.
     4478Given that nested types in C are equivalent to not using them, i.e., they are essentially useless, it is unlikely there are any realistic usages that break because of this incompatibility.
    44914479\end{description}
    44924480
     
    51795167\label{s:RationalNumbers}
    51805168
    5181 Rational numbers are numbers written as a ratio, \ie as a fraction, where the numerator (top number) and the denominator (bottom number) are whole numbers.
     5169Rational numbers are numbers written as a ratio, i.e., as a fraction, where the numerator (top number) and the denominator (bottom number) are whole numbers.
    51825170When creating and computing with rational numbers, results are constantly reduced to keep the numerator and denominator as small as possible.
    51835171
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