Math Notations, Computer Languages, and the “Form” in Formalism

[Xah Lee]

• Math Notations, Computer Languages, and the “Form” in Formalism
http://xahlee.org/cmaci/notation/index.html

plain text version follows. (lacks links)

-----------------------------
Math Notations, Computer Languages, and the “Form” in Formalism

Xah Lee, 2009-08-31

This page is a collection of essays and expositions on the subjects of
nomenclature and notations in math and computer languages, in the
context of facilitating human communication and theorem proving
systems.

Most of these essays here are originally from email, blogs, or rants.
They are not of publication quality, and they are not a coherent
exposition the subject. Here's a very brief summary of of these
essays's central thesis:

• Traditional math notations are very inconsistent. Edsger Dijkstra is
a leader in a movement of what's called Calculational Proofs. That is,
using a notation that is consistent and facilitates the calculation
aspects when doing math by humans.

• Today, especially since 1990s, tremendous advances are made in
computer algebra systems and theorem proving systems. In these
languages, a coherent syntax, grammar, are needed for math
expressions.

• In computer algebra or theorem proving systems, they are intimately
tied to the math philosophies of formalism and logicism. In a sense,
formalism and logicism today are tied together as a single subject,
and using computer languages as foundation.

• Math expressions/syntax in computer languages are intimately tied to
math notations for human reading. (e.g. Mathematical, MathML are
technologies that combine the two.)

• The syntax and grammar of today's computer languages, such as Java,
C, Python, SQL, Lisp, are ad-hoc and their communities have little
understanding of the knowledge gained in math related fields such as
computer algebra or theorem proving languages. (This applies to
functional langs such as Haskell as well, but to a lesser degree.) On
the other hand, mathematicians in general are illiterate about
programing or using computer languages.

All of the above considered together, computer language designers and
mathematicians, should be made aware of these issues, so that when
they design or use computer languages, may it be math oriented or not,
the language's syntax and grammar can move towards a consistent syntax
system with solid foundation (as opposed to ad-hoc), and such language
should have build-in markup or simple mapping to 2-dimensional
notations for human reading (such as done with Mathematica or Semantic
MathML), and this computer language should be in fact as a basis of
theorem prover or computer algebra system (as in OCaml, Haskell,
Mathematica). The languages of computer algebra and theorem prover
would in fact merge together into one single subject if it is not
already slowly happening today.

Progress in the above issues are made in different fields but there
are little unification going on.

For example, there's Edsger Dijkstra's Calculational Proofs movement.
It improves math notations towards consistency and formalism. However,
people in Calculational Proofs movement are mostly math pedagogy
community i think. They are not programers interested in computer
languages, nor logicians interested in math formalism, or industrial
and commercial organizations interested in math notation
representation systems.

There's the computer algebra community, such as Mathematica, Maple,
Matlab, which requires a syntax and grammar for mathematical concepts.
There's the theorem proving community, such as OCaml, Coq, HOL, which
not only requires a syntax for math concepts, but also made major
understanding about math as a system of forms, i.e. formal systems.
Both computer algebra and theorem proving systems require math
notations and computer language syntax that are consistent and can
represent math concepts. However, the 2 camps are largely separate
communities. For example, there is as far as i know no tool that is
both a practical computer algebra system as well as a theorem proving
language.

Common computer languages, such as C, Java, Python, requires a good
syntax, parsers, and compilers, but their community, including
computer scientists and programers, are usually illiterate in typical
topics of of mathematics proper. Functional languages, such as Scheme
Lisp, APL, OCaml, Haskell, are more based on logic foundations (lambda
calculus) but their syntax and grammar has little to do with the math
notations as a logic or formal system. (these languages do not have a
formal spec in the sense of Formlism, i.e. transformation of forms. In
fact, almost no languages has a formal spec, formalism or not.)

There's math notation representation needs, such as TeX, MathCAD,
MathML, Mathematica. These are typically commercial organizations in
the computing industry. They can render math notations. In the case of
MathML and Mathematica, the language also represent the semantic
content of math notations. These two made major understanding about
the relation of math notations and computer languages, but they in
general have little to do with formalism or theorem proving. (with
some exception of Mathematica)

Calculational proof notational system, Computer algebra systems,
theorem prover languages, formalism and logicism as foundation of
mathematics, functional languages, and computer languages in general,
mathematics and its notations, all are in fact can be considered as a
single subject with a unified goal. All the technologies and movements
exist, but today they have mostly not come together. For example,
Microsoft Equaton Editor, TeX, and various other tools does well with
math notation rendering. MathML has both representational and semantic
aspects (OpenMath is a new group that focus on semantic aspects), for
the purpose of rendering as well semantic representation. Mathematica
is a computer algebra system for solving arbitrary math equations,
that is also able to represent math notation as a computer language,
so that computation can be done with math notation directly. However,
the system lacks a foundation as a theorem prover. Theorem provers
such as OCaml (HOL, Coq), Mizar does math formalism as a foundation,
also function as a generic computer language, but lacks abilities as a
computer algebra system or math notation representation.

Notations

* The Codification of Mathematics
* State Of Theorem Proving Systems 2008
* The Problems of Traditional Math Notation

* A Notation for Plane Geometry

* the Moronicity of the Expositions of Common Mathematicians
(rant)

* Fundamental Problems of Lisp (see section 1, on the importance
for regularity of syntax)
* The Concepts and Confusions of Prefix, Infix, Postfix and Fully
Functional Notations
* The Moronicities of Typography

Jargons

Math

* Math Terminology and Naming of Things
* Math Jargons Explained
* Politics and the English Language, 1946, by George Orwell.

Harm Of Bad Terminologies In Computing Languages

* The Importance of Terminology's Quality In A Computer Language
* What are OOP's Jargons and Complexities?
* Java's Abuse of the Jargon “Interface” and API
* Jargons of Info Tech Industry
* The Term Currying In Computer Science
* Function Application is not Currying
* Why You should Not Use The Jargon Lisp1 and Lisp2
* The Jargon “Tail Recursion”
* What Is Closure In A Programing Language
* Jargons And High Level Languages (unpolished essay)
* Why You Should Avoid The Jargon “Tail Recursion”
* I Can Not Find A Word Better Than “CAR”

Harm of Mixing Concept of Syntax and Formatting

* The TeX Pestilence
* The Harm of hard-wrapping Lines (harm of confusing syntax with
formatting)
* Tabs versus Spaces in Source Code (harm of treating syntax as
formatting instead of syntax)

Applications of Regular Syntax

* A Text Editor Feature: Syntax Tree Walk (application of syntax)
* A Simple Lisp Code Formatter (application of syntax regularity)

References

* “Mathematica Notation: Past and Future” (2000-10-20), by Stephen
Wolfram, at http://www.stephenwolfram.com/publications/recent/mathml/index.html.
* Functional Mathematics, by Raymond Boute, 2006. http://www.funmath.be/
* Formalized Mathematics, by John Harrison, 1996-08-13.
http://www.rbjones.com/rbjpub/logic/jrh0100.htm
* “How Computing Science created a new mathematical style”. (1990)
By Edsger W Dijkstra. EWD1073
* “Under the spell of Leibniz's dream” (2000) By Edsger W
Dijkstra. EWD1298
* Abuse of notation
* Formal system

 

[slawekk]

Theorem provers
such as OCaml (HOL, Coq), Mizar does math formalism as a foundation,
also function as a generic computer language, but lacks abilities as a
computer algebra system or math notation representation.

Isabelle's presentation layer is well integrated with LaTeX and you
can use math notation in (presentation of) proofs.

Slawekk

 

[Xah Lee]

2009-09-07

Isabelle's presentation layer is well integrated with LaTeX and you
can use math notation in (presentation of) proofs.

in my previous post
http://xahlee.org/cmaci/notation/index.html

it was quickly written and didn't clearly bring about my point.

The point is, that formalism in mathematics, consistency of math
notation issues (for human), math notation language systems (TeX,
Mathematica, MathML), and calculational proof movement (a la Edsger
Dijkstra), and computer algebra systems, and theorem proving systems,
and computer language syntax, all of the above, should be unified into
one single entity, and is today very much doable, in fact much of it
is happening in disparate communities, but as far as i know i do not
think there's any literature that expresses the idea that they should
all be rolled into one.

Let me address this a bit quickly without trying to write some
coherent essay.

few things to note:

----------
• theorem proving systems and computer algebra systems as unified tool
is very much a need and is already happening. (e.g. there's a project
i forgot the name now that tries to make Mathematica into a theorem
proving system a la ocaml)

----------
• theorem proving systems (isabell, hol, coq etc, “proof assistantsâ€
or “automated proof systemsâ€) and mathematics foundation by formalism
should be unified. This active research the past 30 or more years, and
is the explicit goal of the various theorem proving systems.

----------
• math notation consistency issues for human communication, as the
calculational proof movement by Dijkstra, and also Stephen Wolfram
criticism of traditional notation and Mathematica's StandardForm, is
actually one single issue. They should be know as one single issue,
instead of Calculational Proof movement happening only in math
pedagogy community and Mathematica in its own community.

----------
• math notation issues and computer language syntax and logic notation
syntax is also largely the same issue. Computer languages, or all
computer languages, should move towards a formalized syntax system. I
don't think there's much literature on this aspect (in comparison to
other issues i mentioned in this essay). Most of today's computer
languages's syntax are ad hoc, with no foundation, no consistency, no
formal approach. e.g. especially bad ones are Ocaml, and all C-like
langs such as C, C++, Java. Shell langs are also good examples of
extremely ad hoc: e.g. bash, perl, PowerShell. There are langs that
are more based on a consistent syntax system that are more or less can
be reduced to a formal approach. Of those i know includes Mathematica,
XML (and lots derivatives e.g. MathML) and lisps also. Other langs i
don't know much but whose syntax i think are also close to a formal
system are: APL, tcl.

My use of the phrase “syntax with formal foundation†or “syntax
system†is a bit fuzzy and needs more thinking and explanation... but
basically, the idea is that computer language's syntax can be
formalize in the same way we trying to formalize mathematics (albeit
the problem is much simpler), so that the syntax and grammar can be
reduced to few very simple formal rules in parsing it, is consistent,
easy to understand. Mathematica and XML are excellent examples. (note
here that such syntax system does not imply they look simple.
Mathematica is a example.)

the following 2 articles helps in explaining this:

• The Concepts and Confusions of Prefix, Infix, Postfix and Fully
Nested Notations
http://xahlee.org/UnixResource_dir/writ/notations.html

• Fundamental Problems of Lisp
http://xahlee.org/UnixResource_dir/writ/lisp_problems.html

----------

• systems for displaying math, such as TeX, Mathematica, MathML,
should be unified as part of the computer language's syntax. The point
is that we should not have a lang just to generate the display of math
notations such as done by TeX or MathML or Microsoft equation editor
or other tools. Rather, it should be part of the general language for
doing math. (e.g. any computer algebra system or theorem proving
system)

A good example that already have done this since ~1997 is Mathematica.

practically speaking, this means, when you code in a language (say,
Ocaml), you don't just write code, but you can dynamically,
interactively, have your code display math 2D notations, and the info
about formating the notation is part of the computer language, it's
just that your IDE or specialized editor understand your language and
can format it to render 2D notations on the fly (e.g. HTML is such a
lang).

If you know Mathematica, then you understand this. Otherwise, think of
HTML/XML, which is a lang for formatting purposes without
computational ability, yet today there are XML based general purpose
computer languages. This language is a example of several issues in
this essay. i.e. it's syntax is formalized syntax system, it's is a
general purpose computer language, and it has semantics for 2D
notations or arbitrary formatting/rendering such as headers.

----------

As a example of current situation in contrast of the above idea:
suppose you doing some proof using OCaml derived theorem prover.
Sometimes you need to do computer algebra, so you need to call
Mathematica or Maple as supplement. Then often you need to display the
result in math notation. So you'll need to call/output TeX or MathML.
Then Dijkstra objects that your traditional math notation is so
inconsistent, ambiguous, misleading, ad hoc, and does not help or
correspond to the actual mathematical content behind them. So, you
need to invent or re-write your notation to something proposed by the
Calculational Proofs movement or Stephen Wolfram's (proprietary)
Mathematica's StandardForm, that is not ambiguous.

----------

I think what inspired me to arrive at this idea is mostly my
experiences with Mathematica, and my interest in math formalism and
logicism as foundation, and my interest in technologies such as
computer algebra systems and display systems such as MathML and TeX,
and the intricate issues of relation between math notations and
mathematics.

This may sounds like pitching Mathematica, but as far as i know it is
closest as the best example in unifying all these issues. It is a has
a simple syntax system (i.e. the lang's syntax & grammar is not ad
hoc). It is a general computer language. It is a computer algebra
system (e.g. can solve math equations, etc.). The language also
functions as a math notation display system (e.g. like TeX or MathML).
It has a notation (StandardForm) that is compatible with the
calculational proof movement.

What it lacks is functioning as a theorem proving system.

I'm singling out Mathematica because it is a system i know well and
happened to be the most fitting example in this thesis. Note however,
Mathematica is roughly the sole idea of Stephen Wolfram, and its
syntax/grammar, is not the only approach. It just happens to be the
lang that today has unified many of the issues in this essay (as far
as i know). It is relatively easy to design alternative syntax.

Many approaches to this unified language/syntax/notation/mathematics
system are possible. Different communities mentioned above are trying
to unify or advance different aspects. (e.g. as another example i
haven't mentioned above, there's a project in LaTeX that tries to make
its syntax understand the semantics of math notations, as opposed to
sequence of structurally meaningless symbols that renders to
meaningless display... Lots other examples in different tools really)

i'll have to refine this essay for coherency and more concrete
examples, perhaps with screen shots from different tools, syntax
examples in different languages, rendered output in different tools,
notation comparison from different schools, philosophies in formalism
or logicism or computer proofing systems from different
mathematicians, pertinent quotations and excerpts from various
literatures, and more academic references and industrial
publications... but i hope this idea is conveyed reasonably.

Xah
∑ http://xahlee.org/

☄

 

[fortunatus]

• systems for displaying math, such as TeX, Mathematica, MathML,
should be unified as part of the computer language's syntax. ....
☄

to that end you might be interested in Fortress at Sun:

http://projectfortress.sun.com/Projects/Community
http://research.sun.com/projects/plrg/fortress.pdf
http://research.sun.com/spotlight/2007/2007-01-10_fortress.html

 

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Math Notations, Computer Languages, and the “Form †in Formalism  
(lacks links) ----------------------------- Math Notations, Computer
Languages, and the “Form†in Formalism Xah Lee, 2009-08-31 This page
is a collection of essays and expositions on the subjects of
nomenclature and notations in math and computer languages, in the
context of facilitating human communication and ... Aug 31 by Xah Lee
- 4 messages - 3 authors Math Notations, Computer Languages, and the
“ Form†in Formalism   Aatu Koskensilta (e-mail address removed) sci
theorem proving systems, they are intimately tied to the math
philosophies of formalism and logicism. In a sense, formalism and
logicism today are tied together as a single subject, and using
computer ... Aug 31 by Aatu Koskensilta - 4 messages - 3 authors
This Week's Finds in Mathematical Physics (Week 279)   To see this,
note that any guy in h_2(K) has this form: A = t+xy y* tx where t and
x are real elements of K, and y is an arbitrary element. .... They
formulated a supersymmetric model in 6 dimensions using the
quaternions, and speculated about a similar formalism in 10 dimensions
using the octonions: 6) Taichiro ... Sep 6 by Androcles - 4 messages -
3 authors Math Notations, Computer Languages, and the “ Form†in
Formalism   Aatu Koskensilta (e-mail address removed) sci math David C
nonsense, no doubt. But are you really certain that there's no
nonsense out there that's even more pure? Not really. I'm just winging
it. -- Aatu Koskensilta ([email protected]) "Wovon mann ... Sep
1 by Aatu Koskensilta - 4 messages - 3 authors Math Notations,
Computer Languages, and the “Form†in Formalism   David C Ullrich
(e-mail address removed) sci math On Mon, 31 Aug 2009 17:12:20 +0300, Aatu
algebra or theorem proving systems, they are intimately tied to the
math philosophies of formalism and logicism. In a sense, formalism and
logicism today are ... Aug 31 by David C Ullrich - 4 messages - 3

to that end you might be interested in Fortress at Sun:

http://projectfortress.sun.com/Projects/Community
http://research.sun.com/projects/plrg/fortress.pdf
http://research.sun.com/spotlight/2007/2007-01-10_fortress.html

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