Symbol | Definition | |
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\lceil\; \rceil | CEIL, next higher integer. | |
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\lfloor\;\rfloor | FLOOR, next lower integer. | |
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\approx | approximately equal. | |
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>> | much greater than. | |
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! | factorial. | |
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# | number of. | |
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\log\sb{y}x | logarithm base y of x. | |
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\log{x} | natural logarithm of x, base e = 2.71828182846. | |
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\sum\sb{k}f(k) | sum of all f(k) for the integer k's specified}. | |
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xMODy | modulo function, x reduced by y until x< y. | |
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\jop | one of the comparison operators >\ge;=;\ne\;\le\;<. | |
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\and | and, true if both sides are true. | |
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\or | or, true if either side is true. | |
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| | where, precedes a conditional clause. | |
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\dbinter | set intersection. | |
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\dbunion | set union. | |
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\dbsetdif | set difference. | |
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\dbcross | cartesian product. | |
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\dbselect | select tuples from a relation. | |
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\dbproject | project attributes from a relation. | |
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\dbthetajoin{a = b} | join two relations based on equality of the attributes a, b. | |
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\refto | reference connection. | |
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\ownto | ownership connection. | |
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\subto | subset connection. | |
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\subset | subset of. | |
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\in | member of. | |
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\All | for all. | |
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\becomes | becomes. | |
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{ . . . } | enclose a set. | |
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[ . . . ] | enclose a reference. | |
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\propersubset | proper subset. | |
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Operation | Function | |
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a + b | addition. | |
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a - b | subtraction. | |
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a * b | multiplication. | |
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a / b | division. | |
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MOD(a,b) | modulo, integer remainder of division. | |
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a ** b | exponentiation, a to the power b. | |
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a = b | depending on context in PL/1, assignment or equality comparison. | |
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a < b | greater than comparison, true if a greater than b. | |
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a> L{b} | greater or equal comparison, true if a greater or equal to b. | |
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a \AND b | and, true if both a, b true, (& in PL/1). | |
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a \OR b | or, true if either a, b true, (| in PL/1). | |
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\NT c | not, true if c false and vice versa. | |
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s \CAT w | catenation, string s connected to string w
to form a single new string. | |
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s | c | where, do s if the predicate (conditional) clause c is true. | |
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R \DBUNION S | union of relations R and S. | |
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R \DBINTER S | intersection of relations R and S. | |
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R \DBCROSS S | cross product of relations R and S. | |
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R \DBSETDIF S | difference, remove tuples matching S from R. | |
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\DBSELECT R.ex | select tuples of R according to expression ex. | |
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\DBPROJECT R.a | projection of attributes a of R. | |
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R.a\DBJOIN S.b | Join R and S, on equality of attribute values in a and b. | |
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R.a\DBOUTERJOIN S.b | Outerjoin including all tuples . | |
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, | field separator. | |
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\kg | key and goal fields separator. | |
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; | statement separator. | |
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. | termination of computational section. | |
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ss, ... | section ss may be repeated. | |
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[ ss ] | section ss is optional. | |
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{ ss|tt} | sections ss, tt are alternatives. | |
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::= | is defined by. | |
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/* Note */ | explanatory comments. | |
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a.b | qualification of variable b by a higher-level
variable a,\ie, employee.name. | |
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'Word' | character string constant. | |
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_ | (underline) pseudo-alphabetic character without
syntactic meaning used for legibility within variable names, | |
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| In COBOL - is used for this function. | |
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Symbol | Brief definition | Text definition | |
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A | average space required for attribute name | Sec. 3-1-3. | |
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a | number of different attributes in a file | Sec. 3-1-1. | |
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a\toprime | average number of attributes in a record | Sec. 3-1-1, 3-6-3. | |
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B | blocksize | Sec. 2-2. | |
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b | blockcount | Sec. 2-2-2. | |
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btt | block transfer time = B/t | Eq. 2-13. | |
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\Bfr | blocking factor \approx B/R | Eqs. 2-5, 2-6, 2-7, 2-20. | |
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C | Cost factors | Sec. 5-4-6, 5-5-2. | |
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c | computational overhead per record, when not negligible | Sec. 2-3-4. | |
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D | space required for data | Eq. 5-1, Sec 5-3-3. | |
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d | number of records that have been invalidated | Sec. 3-1-3. | |
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e | = 2.718281828459. | |
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\sbscr{F} | subscript denoting a fetch for a specific record | Sec. 3-0-2. | |
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G | space required for an interblock gap | Sec. 2-2-3. | |
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h | classification variable | Sec. 5-4-3. | |
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\sbscr{I} | subscript denoting insertion of a record | Sec. 3-0-2. | |
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j | number of cylinders | Sec. 2-2-1. | |
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K | projection list | Sec. 7-3-2. | |
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{\tbf K } | Kilo or thousand (1024) times. | |
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k | number of tracks per cylinder | Sec. 2-2-5, Table 2-1. | |
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L | load frequency factors; selection list | Sec. 5-1; 7-3-3. | |
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M | multiprogramming factor | Eq. 5-19. | |
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{\tbf M } | Mega or million (1\,048\,576) times. | |
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m | number of available slots for records | Sec. 3-5-1. | |
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\sbscr{N} | subscript denoting getting the next serial record | Sec. 3-0-2. | |
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n | number of records in a file | Sec. 3-1-3. | |
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o | number of records that overflow | Secs. 3-1-3, 3-2-3, 3-3-3, 3-5-3. | |
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P | space required for a pointer | Sec. 2-3-3. | |
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p | collision cost, also probability | Eqs. 3-73, 3-74, 3-79, Fig. 3-23. | |
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q | production demand by a file application | Eq. 5-2, 5-4 to 5-6. | |
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R | space required for a complete record; relation | Sec. 3-0-2; 7-1-1. | |
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\sbscr{RW} | subscript indicating rewriting | Sec. 2-3-6. | |
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r | rotational latency time | Eq. 2-3. | |
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SI | storage space for index | Eq. 3-52. | |
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s | average seek time | Eq. 2-2. | |
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s\toprime | effective seek time | Eqs. 2-15, 2-16. | |
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T | the time required for various operations; set of tuples | Sec. 3-0-2; 7-3. | |
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T\sb{sort} | the time required to sort a file | Eq. 3-11} . | |
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t | transfer rate from a storage unit to processing memory | Sec. 2-2-5. | |
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t\toprime | bulk transfer rate | Eqs. 2-17, 2-18, 2-19. | |
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\sbscr{U} | subscript denoting an update of a record | Sec. 3-0-2. | |
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u | utilization | Eqs. 5-3, 5-7 to 5-18, 5-20. | |
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uf | utilization factor | Eqs. 6-25, 6-29. | |
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V | average space for value part of an attribute | Sec. 3-1-3. | |
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v | number of records updated | Sec. 3-2-3. | |
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w | wait time in queues | Eq. 6-26. | |
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W | wasted space due to gaps per record | Eqs. 2-9, 2-10, 2-11, 2-21. | |
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\sbscr{X} | subscript denoting an exhaustive search | Sec. 3-0-2. | |
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x | number of levels in an index structure, master level | Eq. 3-27, 3-49, 3-97. | |
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\sbscr{Y} | subscript denoting a reorganization of a file | Sec. 3-0-2. | |
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y | fanout ratio | Eq. 3-26, 3-48. | |
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\sbscr{Z} | subscript denoting an update by replacement with a larger record | Sec. 3-0-2. | |
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