Lecture Notes on Technical Writing (Part 1 of 2)
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1. General Guidelines for Technical Writing

Essential Elements in Written Communication
  1. Target (i.e., Anticipated Readers)
  2. Theme (i.e., Primary Objective)
  3. Content (i.e., What to Write)
  4. Organization (i.e., How to Structure Text)
  5. Style (i.e., How to Express in Writing)
In technical writing, the first two (target and theme) must be decided carefully.
Next, the third (content) must be clarified (often incrementally while writing though).
Then, the last two (organization and style) are chosen so that the content is best presented for the target and the theme.

Differences between Technical Writing and General Writing

(quotation from
Kavita Tyagi and Padma Misra, Basic Technical Communication, Revised Ed., p.9, PHI Learning, New Delhi, 2012)
Technical Writing
General Writing
Document Type
All professional, scientific and specialist documents, drafts, reports, letters, papers, theses Literary and other types of writing
Style
Familiar, simple, clear and precise and of evaluating value Poetic, rhetorical or elegant and carries stamp of individuality
Skills
Acquired through practice Creative and innovative with an inborn talent
Format
Strict and well defined so that the reader can understand the organization of document No set pattern and predefined organization
Language
Simple, straightforward, objective, rational and scientific Elegant or creative. Can be poetic, literary or generic
Words
Technical words and their explanation Descriptive and literary composition
Content
Preplanned on the basis of information collected Spontaneous and written on-the-spur of the moment
Profession
Pertains to profession Relates to society in general
Function
Instructs, informs and persuades Amuses, inspires and educates
Diction
It is simple and effective May use complex and long sentences, but the meaning will be clear

This course focuses on documents of the following types listed in decreasing order of their priorities.

The following are good sources of guidelines, tips and tutorials on technical writing.

The following are tutorials specific to writing technical papers.

Remarks on Common Mistakes by Students in Technical Writing

The following is a partial list of remarks on common mistakes in technical writing that were found in students' reports for assignments of my courses at the University of Hawaii at Manoa.
Note that some of the remarks may be limited to the field of computer science.
  1. Do not use the first person singular pronoun "I" even if a paper was written by a single author.
    Similarly, do not use "my" and use "our" instead.
    It is also very unusual to use the second person singular/plural pronoun "you" in a technical article.
      Bad:    I present the time complexity of an algorithm in this paper.
      OK:     We present the time complexity of an algorithm in this paper.
      Better: The time complexity of an algorithm is presented in this paper.   [traditional style:  passive voice]
              This paper presents the time complexity of an algorithm.          [modern style: active voice]
    
    If the subject of a sentence is truly an author or authors, the first person plural pronoun "we" is OK.
    Otherwise, it is recommended to write the subject explicitly and avoid a pronoun unless what the pronoun refers to is definitely obvious to the readers,
    where the subject is an agent of the action (i.e., verb) mentioned in a sentence.
      Bad:    We first sort points in the nondecreasing order of their x-coordinate values.
              Then, we find a closest pair of points.
      Good:   An algorithm first sorts points in the nondecreasing order of their x-coordinate values.
              Then, the algorithm finds a closest pair of points.
    

  2. Write sentences in the simple present tense unless another tense is definitely needed
    (e.g., in the last section "Conclusions", sentences summarizing a paper are written in the past tense).

    Examples:
      "This paper models a problem of finding
      shortest paths from a single source to
      all other vertices in a digraph."
    
      "This paper presents an algorithm for
      determining whether a given positive integer
      is prime."
    

    Examples of Exceptions:
      "In 1883, the puzzle called the Towers of Hanoi was invented
      by the French mathematician Édouard Lucas."
    
      "E. W. Dijkstra proposed a greedy algorithm
      for finding single-source shortest paths in
      1959."
    
      "Although we have presented an O(n log n)
      algorithm for MPT, it remains unknown whether
      the algorithm has an optimum time complexity.
      That will be one of our future research topics."
    

  3. Keep sentences simple and short.
    Avoid to write a lengthy sentence that connects clauses one after another.

  4. Do not use contractions of two words such as "isn't", "can't", "we've", and "haven't".

  5. Do not use the conjunction "so" that is too casual for technical writing.
    Use conjunctions such as "thus", "therefore" and "hence" instead.

  6. Organize a paper hierarchically with sections
    that may be decomposed into subsections
    which are further broken down to paragraphs.
    To begin writing a paper, design "Table of Contents" first as an outline of the paper.
    Then, for each section or subsection, try to list important phrases or sentences
    that will turn into paragraphs by elaborating them.

    → Step-wise Refinement in Top-Down Design

    One Paragraph ←→ One Issue (Modularity)

  7. "Abstract" summarizes a paper, typically within 100 ~ 200 words.
    An abstract of a paper should be written in order to attract potential readers to its main content.
    It is often used to advertise the paper in research indexes and databases for article search.

    "Keywords and Phrases" are sometimes given next to the abstract.

  8. The first section (typically entitled "Introduction") commonly describes some of the following (but not limited to):

  9. Sections are serially numbered
    (The first section is "Introduction" and the last section is "Conclusion").
    "Acknowledgments" and "References" following the last section are not regarded as sections and hence their headings are not numbered.

  10. Make a paper "self-contained" as much as possible
    in the sense that everything is written in the paper and the paper can be understood by reading it.
    Only exceptions are the knowledge expected to readers (such as knowledge that peers should have) and citations from references listed at the end of the paper.

  11. List references in the IEEE Style:
    Refer to pp.5-13 of IEEE Editorial Style Manual

    Each reference should be referred to in the main text at least once by using its label (usually, a serial number).

    Example:

      It is widely known that NP-complete problems
      are time-consuming to solve [2,5].
      .
      .
      .
      References
      [1] E. W. Dijkstra, "A note on two problems
          in connexion with graphs," Numerische
          Mathematik, vol. 1, pp.269-271, 1959.
      [2] M. R. Garey and D. S. Johnson, Computers
          and Intractability:  A Guide to the Theory
          of NP-Completeness, W. H. Freeman and Co.,
          1979.
      .
      .
      .
    

    The IEEE Style requires to list references in the order of occurrences of their citations in the main text,
    although it is also common to list references in the alphabetical order of last names of their first authors
    with tiebreaking by the chronological order of their publication dates.

  12. Be careful to use online documents as references.
    They are not always reliable source of information.
    Double check authoritative source of information such as books and journals specialized to the relevant topic.

  13. Fully justify text to the both sides.

  14. Use proper notations that are common in the presumed field.

  15. A "technical article" unlikely has a table of contents (probably because it is not lengthy) unless it is a thesis or dissertation.
    In contrast, a book usually has a table of contents.

  16. A page number starts from the first page of the first section (or chapter in case of a book).
    A page number is an arabic number and printed typically in the center of the bottom margin,
    although the IEEE class and style file IEEEtran.cls layouts a page number at the upper right or upper left in the top margin for an odd or even page number, respectively.

    If a paper has a cover page, no page number is given to the cover page.

    If there are pages between the cover page and the first page of p.1, you can put a "roman number" as a page number.

  17. "p." stands for a page number and "pp." stands for page-to-page.

  18. Place a symbol just next to the noun word defining the semantics of the symbol, e.g.,
      A nonempty set F of n factories fi (1 ≤ i ≤ n)
    
    where F denotes a set and fi denotes a factory.

  19. Pay attention to capitalization of words.

    Examples:

  20. Do
    Revise a paper several times.

2. Mathematical Writing

Mathematics together with English is the universal language in science and engineering.
In addition, mathematical formulas are often used to describe phenomena in the real world rigorously.
Thus, it is necessary to learn how to express mathematical statements (e.g., theorems), mathematical properties (e.g., math formulas, equalities and inequatilies), mathematical arguments (e.g., proofs), mathematical concepts (e.g., definitions), etc.

The following are informative tutorials to learn mathematical writing with examples.
The former is a good introductory guide for beginners while the latter is especially useful when you write a thesis, a dissertation or a formal technical paper such as a journal paper or a conference paper.

Many beginners of mathematical writing misunderstand that mathematical writing is to use mathematical notations and symbols as much as possible and enumerate mathematical formulas without using a natural language.
That is wrong!

Example 2.1:
Solve the recurrence system f(n) = 3 f(n−1) with the initial condition f(0) = 2.
Bad Example
g(x) = ∑k=0 ak xk
g(x) − 3 x g(x)
= ∑k=0 ak xk − 3 ∑k=1 ak-1 xk
= a0 + ∑k=1 (ak − 3 ak-1) xk
g(x) − 3 x g(x) = a0 = 2
(1 − 3x) g(x) = 2
g(x) = 2/(1 − 3x) = 2 ∑k=0 (3k xk)
        = ∑k=0 2 (3k xk)
        = ∑k=0 (2⋅3k) xk
ak = 2⋅3k
f(n) = 2⋅3n

This solution begins without any definitions.
Readers may be confused about what g(x) represents.
Furthermore, it is very difficult for the readers to comprehend a logical process of deriving f(n) = 2⋅3n in the above solution,
since the above solution does not describe reasoning for deriving an equation or a formula from prior ones at all.

An argument in mathematical writing is commonly organized as follows.
  1. Definitions
  2. Assumptions
  3. Body: A Sequence of Logical Deductions
  4. Conclusion

Many students who are novice in mathematical writing often misuse the equals sign "=" as shown below.

Example 2.2:
Bad
   2y2 = 2x2 + 4x + 2 = 2 (x + 1)2 / 2 = (x + 1)2
= y = x + 1
In this bad example, the mathematical symbol "=" is used incorrectly as well as inconsistently.

Good
The following is a given equation consisting of two variables x and y.
2y2 = 2x2 + 4x + 2
By dividing the both sides of the equation by 2, we have the following.
y2 = x2 + 2x + 1
The right-hand side of the equation can be factorized as follows.
x2 + 2x + 1 = (x + 1)2
Thus, the given equation is transformed as follows.
y2 = (x + 1)2
This quadratic equation has two distinct solutions of y in terms of x: y = x + 1 and y = −(x + 1). Note that there are an infinite number of pairs of x and y that satisfy the given equation.

Therefore, solutions of the given equation are all pairs of x and y that satisfy at least one of the two linear equations y = x + 1 and y = −(x + 1).

Do not use the equals sign "=" for representing logical relationships.
Use "⇒ for an implication and ⇔ for a logical equivalence.
For example, the following bad example
    x4 + 1 = 2x2
= x4 - 2x2 + 1 = 0
= (x2 - 1)2 = 0
= x2 - 1 = 0
= x2 = 1
= x = 1, -1
should be written as follows.
The given equation x4 + 1 = 2x2 is rewritten by moving all terms to the left-hand side as follows.
x4 - 2x2 + 1 = 0
By considering x2 as a varible (say, y = x2), we can apply the well-known factorization formula of a quadratic polynomial (say, y2 - 2y + 1 = (y - 1)2) for factoring the polynomial of degree 4 in the left-hand side as follows.
(x2 − 1)2 = 0
It implies that x2 − 1 = 0. Then, we get the equation x2 = 1. Thus, the given equation has two roots: x = 1 and x = −1.

Remark 2.1:
Some tutorial on mathematical writing suggests that it is bad to write formulas and reasons behind manipulations of formulas in two columns as shown below.
However, in many cases, such a tabular format with two columns is indeed good to visualize a process of transformations of formulas.
f(n) = 8 ( 5 n2 + 7 n5 + 2) / ( (1/2) n2 )                         given a computational complexity function f(n)
= 16( 5 n2 + 7 n5 + 2) / n2                         by mulpiplying 2 to both numerator and denominator
≤ 16( 5 n5 + 7 n5 + 2 n5) / n2       for all n ≥ 1                         since n5 ≥ 1 and n5 ≥ n2 for all n ≥ 1
= 16( 14 n5 ) / n2       for all n ≥ 1                        
= 16( 14 n3 )       for all n ≥ 1                         since nc / nd = n(c−d) for all n ≥ 1 when d ≠ 0
= 224 n3       for all n ≥ 1                         an upper bound O(n3) derived
When reasoning of a transformation from one formula to another is not simple, it is better to describe the reasoning in English instead of a two-column tabular format.

3. An Introduction to Formal Logic

Formal logic is the foundation of technical writing in the following three ways.
Mathematical logic and symbolic logic are often used as synonyms of formal logic while they are formal logic in a little narrow sense.
  1. To express information so that a third party can assimilate it easily and accurately
  2. To organize information so that a third party can quickly comprehend it
  3. To represent a process of reasoning toward a consequence

There are two major types of formal logic that technical writing is based on.
Regarding propositional logic and predicate logic, refer to my lecture notes for ICS141 taught at the University of Hawaii at Manoa.

Propositional Logic

Predicate Logic

How to Compose Sentences Based on Formal Logic

  1. Express in formal logic what you have in your mind
  2. Translate it into English by referring to typical phrases
  3. Revise it by eliminating any ambiguity and simplifying it
Typical English Phrases Corresponding to Logical Connectives and Quantifiers

Conditional p → q
  • If p, then q.
  • p only if q.
  • p implies q.
  • When p, q.
  • p only when q.
  • p is a sufficient condition for q.
  • q is a necessary condition for p.
  • q if p.
  • q follows from p.
  • q, provided p.
  • q is a logical consequence of p.
  • q whenever p.
¬ q → p p unless q.
Biconditional p ↔ q
  • p if and only if q.
  • p iff q.
  • p is equivalent to q.
  • q is equivalent to p.
  • p is a necessary and sufficient condition for q.
  • q is a necessary and sufficient condition for p.
Universal Quantifier ∀
  • for all ...
  • all ...
  • for every ...
  • every ...
  • for any ...
  • any ...
  • for arbitrary ...
  • an arbitrary ...
  • for each ...
  • each ...
Existential Quantifier ∃
  • there exists ... ( such that ... )
  • there is ... ( such that ... )
  • there is at least one ... ( such that ... )
  • there is some ... ( such that ... )
  • for some ...
  • some ...
  • for at least one ...

Other Typical English Phrases in Mathematical Writing

Definitions
  • Let ... be ...
  • Let ... denote ...
Assumptions
  • Assume that ...
  • Suppose that ...
  • Let ...

Example 3.1:
Let p and q be the propositions "The election is decided" and "The votes have been counted," respectively.
Consider to express the compound proposition ¬q ∨ (¬p ∧ q) as an English sentence.

A literal translation is
"The votes have not been counted or the election is not decided and the votes have been counted."
However, the scope of the 2nd operand of "or" is somewhat vague in this sentence.
That is, there is another interpretation of this sentence corresponding to ( ¬q ∨ ¬p ) ∧ q.

To clarify the semantics, it is better to rephrase it by using the commutativity of disjunction and the English phrase "either ... or ..." instead of the single word "or" for disjunction as follows.
Either the election is not decided and the votes have been counted or the votes have not been counted.

Example 3.2:
Assume that the universe is the set ℤ of integers.
Suppose that we use common predicate constants such as = and < (arithmetic comparisons) on ℤ.

Let n(x) denote the predicate "x > 0," e(x) denote the predicate "x is even," o(x) denote the predicate "x is odd," p(x) denote the predicate "x is prime," and q(x,y,z) denote the predicate "x y = z."

The assertion ∀ x [ ( ∃ y [ ¬ q(x,y,x) ] ) → ¬(x = 0) ] in predicate logic is translated into English as follows.
For every integer x, if there exists some integer y such that x times y is not equal to x, then x is not equal to 0.

Example 3.3:
Assume that the universe is the set ℕ of natural numbers.
Let e(m,n) denote the predicate "m is equal to n," g(m,n) denote the predicate "m is greater than n," and f(k,m) denote the predicate "k is a factor of m."

The assertion "p is a prime" is expressed in predicate logic as follows:
g(p,1) ∧ ¬ ∃ k [ ¬ e(k,1) ∧ ¬ e(k,p) ∧ f(k,p) ]

This definition of a prime is expressed in English as follows.
A natural number p is a prime iff p is greater than 1 and there is no factor of p other than 1 and itself p.

Review 3.1:
Assume that the universe of discourse is the set of integers.
Let p(x) denote "x is a prime," o(x) denote "x is odd," v(x) denote "x is even," ℓ(x,y) denote "x is less than y," e(x,y) denote "x is equal to y," and q(x,y,z) denote "xy is equal to z."

Translate the following into the most concise and unambiguous English sentence.

∀ x [ ℓ(0,x) → ∃ y [ q(x,y,x) ∧ ¬ ∃ z [ ¬ e(y,z) ∧ q(x,z,x) ] ] ]

4. Examples

Example 4.1:
For every integer x, if x2 is odd, then x is odd.

Definitions:

An integer n is even iff there is an integer k such that n is equal to 2k.

An integer n is odd iff there is an integer k such that n is equal to 2k + 1.

Example 4.2:
Let p(x) denote the predicate "x2 + 1 < 0."

¬ ∃ x p(x)
This is equivalent to ∀ x [ ¬ p(x) ].

Example 4.3:
Let p(x) denote "x is prime" and q(x,y) denote "x + y is prime."
∃ x [ ∃ y [ p(x) ∧ p(y) ∧ q(x,y) ] ]

Review 4.1:
Prove or disprove the following assertion.

For every real number x, if x3 is irrational, then x is irrational.

5. Exercises

  1. An integer n is said to be even iff n is a multiple of 2 (i.e., there exists an integer k such that n is equal to 2k).
    Prove that x is even iff x2 is even.

    Hint:
    Let p(x) denote the predicate "x is even" and q(x) denote the predicate "x2 is even."
    Then, the above assertion is ∀ x [ p(x) ↔ q(x) ].

    Prove both ∀ x [ p(x) → q(x) ] and ∀ x [ q(x) → p(x) ].

  2. Assume that the universe of discourse is the set ℤ of all integers.
    Prove or disprove the following assertion.

    "If x and y are odd, then the product of x and y is also odd."

  3. Prove or disprove that if an integer is odd, then its square is odd.

  4. Assume that the universe of discourse is the set ℤ of all integers.
    Prove or disprove the following assertion.

    "There is one and only one integer x such that for all y and z, xy is equal to xz."

  5. Prove or disprove that the square root of 2 is irrational,
    i.e., the square root of 2 cannot be expressed as a ratio of two integers.

  6. Let n be an arbitrary integer.
    Prove or disprove that if n is even, then n3 is even.

    Remark:
    To prove this rigorously, we should apply predicate logic that is an extension of propositional logic,
    since "n is even" and "n3 is even" are not propositions (they are called predicates).
    In this exercise, you may write a more informal proof.

  7. Prove that for every integer x, x is even iff x2 is even.

  8. Assume that the universe of discourse is the set ℤ of all integers.
    Prove or disprove the following assertion.

    "If x and y are odd, then the product of x and y is also odd."

  9. Assume that the universe of discourse is the set ℤ of all integers.
    Prove or disprove the following assertion.

    "There is one and only one integer x such that for all y and z, yx is equal to zx."

  10. Prove or disprove that if an integer is even, then its square is even.

  11. Prove or disprove that the square root of 3 is irrational,
    i.e., the square root of 3 cannot be expressed as a ratio of two integers.

  12. Prove the following by induction.

    Σni=1 i2 = n(n + 1)(2n + 1)/6 for all n ∈ ℕ

  13. Prove by induction
    Σni=1 1/((2i-1)(2i+1)) = n/(2n+1) for every positive integer n.

  14. Prove by induction
    Σni=1 i(i+1)(i+2) = n(n+1)(n+2)(n+3)/4.

  15. Show how you derive the probability that when a fair coin is flipped n times an equal number of heads and tails appear.