|
YOU are better than YOU think. Show
yourself how:
|
// _ _ \\
/\ /\
<| (o) (o) |>
\ | | /
-/[]\-
||
/ \_
||||||||||||||||||||||||||||
Logic
chapters 1 to 5 re- appear not in sequence, as is or longer,
in Volume 1A, Pattern Based
Reason, Bon Appetite.
Logic
Mastery
Amazing, Amusing, Amorous, Delicious, Delightful, Edifying,
Strengthening Elixir.
It eases work & learning difficulties Makes the hard easier. Opens eyes.
Leads to greater precision.
in reading and
writing
Logic
mastery makes the hard, easier. Logic
mastery leads to better, stronger and richer comprehension. Logic
mastery improves reading and writing. Logic
mastery ease learning difficulties. Logic
mastery gives a headstart. In sum, logic
mastery will develops critical thinking, improve reading and writing,
and give a firmer base for work and studies at many levels. Good luck.
After logic,
(a) continue reading Three
Skills for Algebra, chapters 8 to 14 and do so alongside site area on solving
liinear Equations ; or (b) see this calculus
starter lesson and Volume 3, Why
Slopes & More Math, chapters 2 to 6;
|
// _ _ \\
/\ /\
<| (o) (o) |>
| |
| |
\
/
\ = /
|
Caution: Site advice is approximately
correct, for some circumstances, not all. That leaves room for thought |
-/[]\-
||
_ / \
||||||||||||||||||||||||||||
What may be learnt and when depends on how skills
and concepts are developed. Making the hard easier and clearer will allow
earlier & richer development of skills and concepts.
Try the Twiddla
Whiteboard. In principle, it allows
to people to draw and chat together online on a copy of this webpage or a clean
sheet. The chat may be via text or audio. Visit www.twiddla.com
to set up whiteboards to work with the webpage of your choice.
For online automated help in senior high school maths & calculus,
visit quickmath.com For Automatic
Calculus and Algebra Help with derivatives, integrals, graphs, linear equations,
matrix algebra, visit calc101.com
With overlap, each site quickmath
& calc101offers a different range of
services, some free, some not, all based on webmathematica. Good luck.
| |
A Possible Start
Students need to know how to count. A knowledge of how
counting might of began with tally marks on tally sticks (or walls) may
provide a context.
Tally marks on a stick may have given the earliest way for an individual to
keep track of how many objects possessed or owed.

As long as there is a one-to-one pairing, matching or correspondence between
the tally marks and the objects being tracked, the owner assumes none have been
lost or gained. The tally marks altogether describe and visually count or keep
track of how many objects there
are.
For example, a shepherd may put a tally mark on the tally stick above for each sheep that enters a
pen, and later on verify as the sheep leave the pen that there is still one mark
per sheep. That keeps track of the sheep and ensures none have been lost nor
gain. Births and predators are assumed to account for all changes in the
correspondence. If the tally marks are all alike as they are made, the order in
which sheep leave the pen may be different from then one the entered. All that
is important in concluding that no sheep has been gains or lost is that each
sheep on exit be in one to one correspondence with a tally mark and that all
tally marks are used.
In pure mathematics, two sets are said to be have the same
cardinality (count) or to be equipollent when and only when there is a bijection
or one-toone-correspondence between
them. A bijection in brief is a one to one pairing between the elements
of one set and the elements of the other, so all elements in each set belong along to
one and only one ordered pair. Tracking sheep or marbles with tally
marks on a stick (or paper) provides a bijection between the set of tally
marks and the set of sheep.
The shepherd in keep track of his sheep may have tally marks on several
sticks. In that case, the sheep may be allowed to exit the pen via several
exits. Again as long this exiting gives a one to one pairing between the sheep
and tally marks, the shepherd and we assume none have been lost. The sheep
could be tallied in the first instant by entering the pen via several entrances
or in several groups. It is possible to allow the sheep to enter grouped
in one way and to leave grouped in another way. And if we tallied the
entering and leaving each day using different tally ticks, and different
groupings of the sheep and tally sticks, the different tallies and the
sheep should be in one to one correspondence.
Working Definition of Whole Numbers: A set of tally marks on a
stick gives a whole numbers. So whenever we speak of a whole number, we think of
a set of distinct tally marks on a real or imagined stick.
Assumption
|
Tallying or Enumeration Assumption: If a set is tallied (counted) in two different ways, with or
without the use of grouping, the set of tally marks for one way will lie in a
bijection (one to one correspondence) with the marks in the other way.
In other words, we assume any two ways to count the elements of a set
will result in the same number. Later on, we will see that the
equality of two ways to count or measure what is a set or region leads to
properties of arithmetic.
First Tallying or Enumeration Assumption: For a person who can count,
the number of tally marks will be the same regardless of the order in which
the elements of a set are tallied or counted.
Remark for Students of Pure Mathematics:
The following gives a set theoretic justification of the unique tallying
or enumeration principle
Two sets are equipotent when and only when there is a
one-to-one
map from one onto the the other. The latter notion works for both finite and infinite sets as
well.
Theorem: If there is a one-to-one map f of a set
U into a proper subset W of itself then the set is not finite:
Proof If U has N elements and we can find a
one-to-one labeling of those N elements u of U given by a map
c(j): [1,N] -> U. Now d(j) = f(c(j)): [1,N] -> W, a proper
subset of U. Therefore, there is an element s in U not W. Pick such an
s and Put d(N+1) = s. Then the extended map d:
[1,N+1] -> U has a range with N+1 elements in U. The
foregoing shows that if we count N distinct elements in U with the aid
of the mapping c then with the aid of the mapping f, we
can also count N+1 elements as well using another function d. Therefore
for all whole numbers N, there is no bijective map of a range of
whole numbers 1 to N onto U. That is what we mean by saying the set U
is finite.
Contrapostive form of theorem: If U is a finite set
(that is, is in bijective correspondence with a set of whole numbers 1
to N) then then any one-to-one map of U into itself must be
surjective. - if it was not then U would be not finite,
that is infinite.
Unique Tallying Theorem: If P is a finite set
with two maps c: [1,N] --> U and d:[1,M] --> U are
bijections of two possibly different intervals [1,N] and [1,M] then N
= M.
Proof: If N < M then for each j in the interval
[1,M], there is a unique u = d(j) in P and hence a unique
k = c-1(u) = c-1( d(j) ) = f(j) in [1, N]
and hence in [1,M] Therefore f:[1,M] --> [1,M] is an injection.
Yet [1,M] is finite. So the injection must be surjective and hence
N = M. The alternative possibility M < N is
treated similarly. Q.E.D.
Note each of the maps in the Unique Tallying theorem represents a
way to count the number of elements in the set P
|
|
Collecting the tally marks into groups provided a counting or
numeration. Today, we go further. In decimal notation we use digits 1 to 9
to as marks for single object or a group of them, and we use place value to keep
track of how ones, tens, hundreds, thousands etc there are in a count. So
we track groups of power of ten instead of individual elements of a set or sheep
in a pen. None the less, tallying goes on. And when we are counting elements of
a set, we assume the final count or the decimal for it will be independent of
how and in which order the set elements are tallied, counted or numbered.
Decimals
Decimal notation provides a compact form of tally marks for tallying or
counting or describing how many objects there are in a set. The decimal view of
numbers and number theory may be read parallel to the general number theory
pages.
The Start of Number Theory Continues with the following pages
Adding Wholes Multipling
Wholes Distributive
Law Preamble
Distributive Law for Wholes Consequences
More
Consequences
What is a Fraction Compound
Fractions
after this one (and not the next links in top and bottom margins
| |
www.whyslopes.com
Number Theory
Start of Number Theory
Origins of Counting or Tallying
Adding Wholes
Multipling Wholes
Distributive Law Preamble
Distributive Law for Wholes
Consequences
More Consequences
What is a Fraction
Compound Fractions
Number Theory
Continued
Decimal Place Value Comparison Method Addition Method Subtraction Methods Multiplication Methods Division Methods Remainder Arithmetic I Primes & Composites Primes Factorization Primes & Composites Prime Factorization Aids Prime Factorization Examples Counting Whole No. Factors Arithmetic Videos Square Roots Fractions & Decimals Fractions as Decimals 1 = 0.999 Recurring Long Division Continued Ratio of Simple Fractions Ratio of Decimal Fractions Unsigned Reals Numbers Signed Coordinates Plane Vectors Horizontal Vectors How to Add Reals How to Multiply Reals Distributive Law for Reals Remainder Arithmetic II
Related Site Pages:
|