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on cut edges and bonds, graph theory

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  on cut edges and bonds, graph theory Daniel Bastos <dbastos@toledo.com> - 2017-09-18 12:51 -0300
    Re: on cut edges and bonds, graph theory Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-09-18 20:40 +0100
      Re: on cut edges and bonds, graph theory William Elliot <marsh@panix.com> - 2017-09-18 21:39 -0700
        Re: on cut edges and bonds, graph theory Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-09-19 13:05 +0100
          Re: on cut edges and bonds, graph theory William Elliot <marsh@panix.com> - 2017-09-19 19:47 -0700
            Re: on cut edges and bonds, graph theory Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-09-20 14:28 +0100
              Re: on cut edges and bonds, graph theory William Elliot <marsh@panix.com> - 2017-09-20 21:06 -0700
                Re: on cut edges and bonds, graph theory Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-09-21 17:03 +0100
                  Re: on cut edges and bonds, graph theory Daniel Bastos <dbastos@toledo.com> - 2017-09-21 15:06 -0300
                    Re: on cut edges and bonds, graph theory Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-09-21 21:24 +0100
                      Re: on cut edges and bonds, graph theory Daniel Bastos <dbastos@toledo.com> - 2017-09-21 17:57 -0300
                        Re: on cut edges and bonds, graph theory Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-09-21 23:40 +0100
                  Re: on cut edges and bonds, graph theory William Elliot <marsh@panix.com> - 2017-09-21 20:45 -0700
                    Re: on cut edges and bonds, graph theory Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-09-23 02:27 +0100
                      Re: on cut edges and bonds, graph theory William Elliot <marsh@panix.com> - 2017-09-22 19:49 -0700
                        Re: on cut edges and bonds, graph theory Richard Heathfield <rjh@cpax.org.uk> - 2017-09-23 08:04 +0100
                          Re: on cut edges and bonds, graph theory Daniel Bastos <dbastos@toledo.com> - 2017-09-23 08:41 -0300
                          Re: on cut edges and bonds, graph theory Paul N <gw7rib@aol.com> - 2017-09-24 14:00 -0700
                        Re: on cut edges and bonds, graph theory Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-09-23 14:50 +0100
                          Re: on cut edges and bonds, graph theory William Elliot <marsh@panix.com> - 2017-09-23 22:04 -0700
                            Re: on cut edges and bonds, graph theory Richard Heathfield <rjh@cpax.org.uk> - 2017-09-24 07:39 +0100
                              Re: on cut edges and bonds, graph theory William Elliot <marsh@panix.com> - 2017-09-25 01:13 -0700
                                Re: on cut edges and bonds, graph theory Richard Heathfield <rjh@cpax.org.uk> - 2017-09-25 09:46 +0100
                                  Re: on cut edges and bonds, graph theory William Elliot <marsh@panix.com> - 2017-09-25 21:38 -0700
                                    Re: on cut edges and bonds, graph theory Richard Heathfield <rjh@cpax.org.uk> - 2017-09-26 10:19 +0100
                                      Modern Trash William Elliot <marsh@panix.com> - 2017-09-26 03:37 -0700
                                        Re: Modern Trash David Brown <david.brown@hesbynett.no> - 2017-09-26 12:52 +0200
                                        Re: Modern Trash Richard Heathfield <rjh@cpax.org.uk> - 2017-09-26 23:10 +0100
                            Re: on cut edges and bonds, graph theory Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-09-24 22:33 +0100
                              Re: on cut edges and bonds, graph theory William Elliot <marsh@panix.com> - 2017-09-25 01:08 -0700
                                Re: on cut edges and bonds, graph theory Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-09-25 20:44 +0100
                                  Re: on cut edges and bonds, graph theory William Elliot <marsh@panix.com> - 2017-09-25 21:36 -0700
                                    Re: on cut edges and bonds, graph theory Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-09-26 12:04 +0100
                                      Re: on cut edges and bonds, graph theory William Elliot <marsh@panix.com> - 2017-09-26 23:15 -0700
                                        Re: on cut edges and bonds, graph theory Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-09-27 12:52 +0100
                                          Re: on cut edges and bonds, graph theory William Elliot <marsh@panix.com> - 2017-09-27 19:55 -0700
                      Re: on cut edges and bonds, graph theory Ike Naar <ike@iceland.freeshell.org> - 2017-09-24 16:55 +0000
          Re: on cut edges and bonds, graph theory David Brown <david.brown@hesbynett.no> - 2017-09-22 10:23 +0200
            Re: on cut edges and bonds, graph theory Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-09-22 21:18 +0100
              Re: on cut edges and bonds, graph theory Daniel Bastos <dbastos@toledo.com> - 2017-09-23 08:48 -0300
              Re: on cut edges and bonds, graph theory David Brown <david.brown@hesbynett.no> - 2017-09-25 10:17 +0200
                Re: on cut edges and bonds, graph theory Daniel Bastos <dbastos@toledo.com> - 2017-09-25 07:31 -0300
                  Re: on cut edges and bonds, graph theory David Brown <david.brown@hesbynett.no> - 2017-09-25 13:30 +0200
                Re: on cut edges and bonds, graph theory Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-09-25 20:32 +0100
                  Re: on cut edges and bonds, graph theory David Brown <david.brown@hesbynett.no> - 2017-09-26 10:12 +0200
                    Re: on cut edges and bonds, graph theory Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-09-26 11:53 +0100
                      Re: on cut edges and bonds, graph theory David Brown <david.brown@hesbynett.no> - 2017-09-26 13:24 +0200
      Re: on cut edges and bonds, graph theory Daniel Bastos <dbastos@toledo.com> - 2017-09-19 16:21 -0300
        Re: on cut edges and bonds, graph theory Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-09-20 17:43 +0100
          Re: on cut edges and bonds, graph theory Daniel Bastos <dbastos@toledo.com> - 2017-09-21 16:20 -0300
            Re: on cut edges and bonds, graph theory Daniel Bastos <dbastos@toledo.com> - 2017-09-21 17:52 -0300
            Re: on cut edges and bonds, graph theory Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-09-21 22:02 +0100
              Re: on cut edges and bonds, graph theory Daniel Bastos <dbastos@toledo.com> - 2017-09-23 13:42 -0300

Page 1 of 3  [1] 2 3  Next page →

#8011 — on cut edges and bonds, graph theory

This is a question on the definition of cut edges, edge cuts and bonds
as given by section 2.2, page 27-29 of

  ``Graph theory with applications'' by J.A. Bondy and U.S.R. Murty,
  Department of Combinatorics and Optimization, University of Waterloo,
  Ontario, Canada.  North-Holland, fifth printing, 1982.  ISBN:
  0-444-19451-7.

I understand cut edges.  It's defined in page 27.

Definition (cut edge).  A cut edge of G is an edge e such that 
w(G - e) > w(G), where w(G) means the number of components of G.

It says e is a a cut edge if removing e from G yields more components
than we had before.  In other words, e is necessary to keep G with the
components it had.  (In particular, if G is connected, then e is
necessary to keep G connected.)

No problem here.

On page 29, edge cuts are defined.  (My writing.)

Notation (separation).  For subsets S and S' of V, we denote [S, S'] the
set of edges with one end in S and the other in S'.

Question.  It seems [S, S'] is a separation of G into two parts.  Does
it mean [S,S'] contains all possible (x,y) edges for x in S, y in S'?

Although the book gave me Figure 2.4 (a), it didn't give me S and S', so
I'm not sure which vertices of the picture would be in S.

Thank you!

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#8012

Daniel Bastos <dbastos@toledo.com> writes:

> This is a question on the definition of cut edges, edge cuts and bonds
> as given by section 2.2, page 27-29 of
>
>   ``Graph theory with applications'' by J.A. Bondy and U.S.R. Murty,
>   Department of Combinatorics and Optimization, University of Waterloo,
>   Ontario, Canada.  North-Holland, fifth printing, 1982.  ISBN:
>   0-444-19451-7.
>
> I understand cut edges.  It's defined in page 27.
>
> Definition (cut edge).  A cut edge of G is an edge e such that 
> w(G - e) > w(G), where w(G) means the number of components of G.
>
> It says e is a a cut edge if removing e from G yields more components
> than we had before.  In other words, e is necessary to keep G with the
> components it had.  (In particular, if G is connected, then e is
> necessary to keep G connected.)
>
> No problem here.
>
> On page 29, edge cuts are defined.  (My writing.)
>
> Notation (separation).  For subsets S and S' of V, we denote [S, S'] the
> set of edges with one end in S and the other in S'.
>
> Question.  It seems [S, S'] is a separation of G into two parts.

I don't know what a separation is, but this seems like an unlikely term.
For example [V, V] = E.  Does your "(my writing)" mean the term
"separation" is your own?

> Does
> it mean [S,S'] contains all possible (x,y) edges for x in S, y in S'?

I'm worried by the phrasing simply because I wonder why you want to
re-word the definition:

  For subsets S and S' of V, we denote [S, S'] the set of edges with one
  end in S and the other in S'

That sounds clear to me.  I think you mean the same when you talk about
all possible edges for x in S and y in S' but I'm not 100% sure.

> Although the book gave me Figure 2.4 (a), it didn't give me S and S', so
> I'm not sure which vertices of the picture would be in S.

An edge cut (such as that illustrated in Fig. 2.4 (a)) is a special case
of [S, S'] where S' = V\S and S is a non-empty proper subset of V.  The
book uses an over bar for that case: [S, S̅].

For [A, B] to be an edge cut, A ∪ B = V, A ∩ B = {}, A =/= {} and B =/=
{}.  There's really no choice about what vertices are in the two sets
for Fig. 2.4 (a).

> Thank you!

-- 
Ben.

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#8013

On Mon, 18 Sep 2017, Ben Bacarisse wrote:

> Daniel Bastos <dbastos@toledo.com> writes:
> 
> > This is a question on the definition of cut edges, edge cuts and bonds
> > as given by section 2.2, page 27-29 of
> >
> >   ``Graph theory with applications'' by J.A. Bondy and U.S.R. Murty,
> >   Department of Combinatorics and Optimization, University of Waterloo,
> >   Ontario, Canada.  North-Holland, fifth printing, 1982.  ISBN:
> >   0-444-19451-7.
> >
> > I understand cut edges.  It's defined in page 27.
> >
> > Definition (cut edge).  A cut edge of G is an edge e such that 
> > w(G - e) > w(G), where w(G) means the number of components of G.
> >
> > It says e is a a cut edge if removing e from G yields more components
> > than we had before.  In other words, e is necessary to keep G with the
> > components it had.  (In particular, if G is connected, then e is
> > necessary to keep G connected.)
> >
> > No problem here.
> >
> > On page 29, edge cuts are defined.  (My writing.)
> >
> > Notation (separation).  For subsets S and S' of V, we denote [S, S'] the
> > set of edges with one end in S and the other in S'.
> >
> > Question.  It seems [S, S'] is a separation of G into two parts.
> 
> I don't know what a separation is, but this seems like an unlikely term.
> For example [V, V] = E.  Does your "(my writing)" mean the term
> "separation" is your own?
> 
> > Does
> > it mean [S,S'] contains all possible (x,y) edges for x in S, y in S'?
> 
> I'm worried by the phrasing simply because I wonder why you want to
> re-word the definition:
> 
>   For subsets S and S' of V, we denote [S, S'] the set of edges with one
>   end in S and the other in S'
> 
> That sounds clear to me.  I think you mean the same when you talk about
> all possible edges for x in S and y in S' but I'm not 100% sure.
> 
> > Although the book gave me Figure 2.4 (a), it didn't give me S and S', so
> > I'm not sure which vertices of the picture would be in S.
> 
> An edge cut (such as that illustrated in Fig. 2.4 (a)) is a special case
> of [S, S'] where S' = V\S and S is a non-empty proper subset of V.  The
> book uses an over bar for that case: [S, S?E].
> 
> For [A, B] to be an edge cut, A ?H? B = V, A ?H? B = {}, A =/= {} 
and B =/=
> {}.  There's really no choice about what vertices are in the two sets
> for Fig. 2.4 (a).
> 
What does S?E and ?H? mean?

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#8014

William Elliot <marsh@panix.com> writes:

> On Mon, 18 Sep 2017, Ben Bacarisse wrote:
<snip>
>> ...  The book uses an over bar for that case: [S, S?E].
>> 
>> For [A, B] to be an edge cut, A ?H? B = V, A ?H? B = {}, A =/= {} and
>> B =/= {}.
<snip>
> What does S?E and ?H? mean?

They means that some software has had trouble with the Content-Type of
my post.  They are the transliteration chosen by that software for byte
sequences representing a combining overline, set union and set
intersection.

-- 
Ben.

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#8016

On Tue, 19 Sep 2017, Ben Bacarisse wrote:
> William Elliot <marsh@panix.com> writes:

> >> ...  The book uses an over bar for that case: [S, S?E].
> >> 
> >> For [A, B] to be an edge cut, A ?H? B = V, A ?H? B = {}, A =/= {} and
> >> B =/= {}.
> <snip>
> > What does S?E and ?H? mean?
> 
> They means that some software has had trouble with the Content-Type of
> my post.  They are the transliteration chosen by that software for byte
> sequences representing a combining overline, set union and set
> intersection.

Usenet is old fashion.  Such stuff doesn't communicate well.
We use various other plain text symbols for intersection and union.

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#8017

William Elliot <marsh@panix.com> writes:

> On Tue, 19 Sep 2017, Ben Bacarisse wrote:
>> William Elliot <marsh@panix.com> writes:
>
>> >> ...  The book uses an over bar for that case: [S, S?E].
>> >> 
>> >> For [A, B] to be an edge cut, A ?H? B = V, A ?H? B = {}, A =/= {} and
>> >> B =/= {}.
>> <snip>
>> > What does S?E and ?H? mean?
>> 
>> They means that some software has had trouble with the Content-Type of
>> my post.  They are the transliteration chosen by that software for byte
>> sequences representing a combining overline, set union and set
>> intersection.
>
> Usenet is old fashion.  Such stuff doesn't communicate well.

I prefer to think of some software as old fashioned.  With a little
help, Usenet is fit for the 21st Century.

> We use various other plain text symbols for intersection and union.

Who is "we"?

-- 
Ben.

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#8019

On Wed, 20 Sep 2017, Ben Bacarisse wrote:
> William Elliot <marsh@panix.com> writes:
> >
> >> >> ...  The book uses an over bar for that case: [S, S?E].
> >> >> 
> >> >> For [A, B] to be an edge cut, A ?H? B = V, A ?H? B = {}, A =/= {} and
> >> >> B =/= {}.
> >> > What does S?E and ?H? mean?
> >> 
> >> They means that some software has had trouble with the Content-Type of
> >> my post.  They are the transliteration chosen by that software for byte
> >> sequences representing a combining overline, set union and set
> >> intersection.
> >
> > Usenet is old fashion.  Such stuff doesn't communicate well.

It worked much better than the new fangled stuff.
One example is mathstack.

> I prefer to think of some software as old fashioned.  With a little
> help, Usenet is fit for the 21st Century.

The new fangled stuff might work better were it designed better, 
standardized special characters and didn't throw in the kitchen sink, 
ie cram it with too much stuff.

> > We use various other plain text symbols for intersection and union.
> 
> Who is "we"?

Those of us who wrote, learned and taught math in plain text ascii on 
Usenet.  TeX is a hideous language to have to write.  Often writing
out the math in English is more proficient than writing TeX.

I have notice that over the years, as I was forced to modernized, that 
my productivity has fallen for being hampered by all that new fangled 
stuff.  Windows as an operation system is a disaster designed for 
dummies who won't have to be bother learning how to use an effective 
operating system.  Now the computer, with mikes and cameras, is just a 
spy in your home.  The web is going from an excellent means of 
communication to a piece of commercial trash, much the same way
that radio and TV has but with the added advantage of spying on you
by both corporations and governments.  Now under the rubric of fake 
news, people are being censored;  left wing groups among others are 
targeted.  So like the radio and TV - just silly entertainment, ads 
and government propaganda - the web is becoming such.

New and improved is never as good.

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#8020

William Elliot <marsh@panix.com> writes:

> On Wed, 20 Sep 2017, Ben Bacarisse wrote:
>> William Elliot <marsh@panix.com> writes:
>> >
>> >> >> ...  The book uses an over bar for that case: [S, S?E].
>> >> >> 
>> >> >> For [A, B] to be an edge cut, A ?H? B = V, A ?H? B = {}, A =/= {} and
>> >> >> B =/= {}.
>> >> > What does S?E and ?H? mean?
>> >> 
>> >> They means that some software has had trouble with the Content-Type of
>> >> my post.  They are the transliteration chosen by that software for byte
>> >> sequences representing a combining overline, set union and set
>> >> intersection.
>> >
>> > Usenet is old fashion.  Such stuff doesn't communicate well.
>
> It worked much better than the new fangled stuff.
> One example is mathstack.

Eh?  I post on Usenet because it works well -- much better than
mathstack.

>> I prefer to think of some software as old fashioned.  With a little
>> help, Usenet is fit for the 21st Century.
>
> The new fangled stuff might work better were it designed better, 
> standardized special characters and didn't throw in the kitchen sink, 
> ie cram it with too much stuff.

When it comes to standards, it's inevitable that many people -- even
most -- will be disappointed.  But it's done now and it works well
enough.

>> > We use various other plain text symbols for intersection and union.
>> 
>> Who is "we"?
>
> Those of us who wrote, learned and taught math in plain text ascii on 
> Usenet.

Ah, right.  It's an odd word to use since I too learned that but I
appear not to be included in the "we".

(A word of caution in case you don't know... It can come over as rather
grand to say "we do X" when you just mean that you are among the set of
people who do X.)

> TeX is a hideous language to have to write.  Often writing
> out the math in English is more proficient than writing TeX.
>
> I have notice that over the years, as I was forced to modernized, that 
> my productivity has fallen for being hampered by all that new fangled 
> stuff.  Windows as an operation system is a disaster designed for 
> dummies who won't have to be bother learning how to use an effective 
> operating system.  Now the computer, with mikes and cameras, is just a 
> spy in your home.  The web is going from an excellent means of 
> communication to a piece of commercial trash, much the same way
> that radio and TV has but with the added advantage of spying on you
> by both corporations and governments.  Now under the rubric of fake 
> news, people are being censored;  left wing groups among others are 
> targeted.  So like the radio and TV - just silly entertainment, ads 
> and government propaganda - the web is becoming such.
>
> New and improved is never as good.

Oh, OK.  That's not been my experience.  My new and improved CPU is way
better than the one in the DG Nova I first used, and it does not need
cooling water like the IBM 370 either.  I much prefer to type into Emacs
than punch cards or tapes.  I love my delete key -- re-punching cards
was a royal pain, despite the handy DUP key.  In fact, I don't know how
we could even be having the conversation on the kind of machine I
started on.

-- 
Ben.

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#8021

Ben Bacarisse <ben.usenet@bsb.me.uk> writes:

[...]

>> New and improved is never as good.
>
> Oh, OK.  That's not been my experience.  My new and improved CPU is way
> better than the one in the DG Nova I first used, and it does not need
> cooling water like the IBM 370 either.  I much prefer to type into Emacs
> than punch cards or tapes.  I love my delete key -- re-punching cards
> was a royal pain, despite the handy DUP key.  In fact, I don't know how
> we could even be having the conversation on the kind of machine I
> started on.

You used a computer that needed cooling water?  That's amazing!  I
hadn't even heard of something like that.  Which year were you using the
IBM 370, if I may ask?

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#8023

Daniel Bastos <dbastos@toledo.com> writes:

> Ben Bacarisse <ben.usenet@bsb.me.uk> writes:
>
> [...]
>
>>> New and improved is never as good.
>>
>> Oh, OK.  That's not been my experience.  My new and improved CPU is way
>> better than the one in the DG Nova I first used, and it does not need
>> cooling water like the IBM 370 either.  I much prefer to type into Emacs
>> than punch cards or tapes.  I love my delete key -- re-punching cards
>> was a royal pain, despite the handy DUP key.  In fact, I don't know how
>> we could even be having the conversation on the kind of machine I
>> started on.
>
> You used a computer that needed cooling water?  That's amazing!  I
> hadn't even heard of something like that.  Which year were you using the
> IBM 370, if I may ask?

1978.  That was just submitting jobs remotely and I am guessing that the
370 was water cooled.  The high-end ones were and this was at a major
facility (Cambridge University).  At the time I was actually coding for
an IBM 360 locally and that one also needed water cooling.  I remember
the figure of 25 gallons an hour at 15 degrees but it was so long ago
that I may just be making that up.  I can't find any reference for the
actual amount required.

-- 
Ben.

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#8025

Ben Bacarisse <ben.usenet@bsb.me.uk> writes:

> Daniel Bastos <dbastos@toledo.com> writes:
>
>> Ben Bacarisse <ben.usenet@bsb.me.uk> writes:
>>
>> [...]
>>
>>>> New and improved is never as good.
>>>
>>> Oh, OK.  That's not been my experience.  My new and improved CPU is way
>>> better than the one in the DG Nova I first used, and it does not need
>>> cooling water like the IBM 370 either.  I much prefer to type into Emacs
>>> than punch cards or tapes.  I love my delete key -- re-punching cards
>>> was a royal pain, despite the handy DUP key.  In fact, I don't know how
>>> we could even be having the conversation on the kind of machine I
>>> started on.
>>
>> You used a computer that needed cooling water?  That's amazing!  I
>> hadn't even heard of something like that.  Which year were you using the
>> IBM 370, if I may ask?
>
> 1978.  That was just submitting jobs remotely and I am guessing that the
> 370 was water cooled.  The high-end ones were and this was at a major
> facility (Cambridge University).  At the time I was actually coding for
> an IBM 360 locally and that one also needed water cooling.  I remember
> the figure of 25 gallons an hour at 15 degrees but it was so long ago
> that I may just be making that up.  I can't find any reference for the
> actual amount required.

I've got probably a lot more questions, if that's okay.  How was the
programming cycle in details?  Say you wrote Fortran back then.  (What
were you writing?)  You'd write Fortran maybe on paper.  You think you
have you program right.  Now what?  Was there a compiler to help?  You
had no video to echo back what you were working on?

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#8027

I've trimmed the algebra group since this is all programming.

Daniel Bastos <dbastos@toledo.com> writes:
<snip>
> I've got probably a lot more questions, if that's okay.

Sure.

> How was the
> programming cycle in details?  Say you wrote Fortran back then.  (What
> were you writing?)

Yes, FORTRAN IV (which was almost exactly the 1966 standard).  Fortran
77 had just come out but compilers were either nonexistent or very
expensive.  I also wrote toy programs in Lisp, B (a precursor to C),
SASL (a precursor to Haskell) and a very nice teaching Algol variant
called S-Algol.

The B compiler was on a Honeywell mainframe and that was accessed via a
terminal.  SASL and S-Algol ran on a Unix machine in other room, again
access via a terminal.  At the time there was no full-screen editor,
though these were, technically, just about feasible on the hardware.
You edited programs using the "ed".  Still available on Linux if you
want to know how that was done.

> You'd write Fortran maybe on paper.  You think you
> have you program right.  Now what?  Was there a compiler to help?  You
> had no video to echo back what you were working on?

For the IBM 360 (and for remote jobs to the 370) you'd write the program
on paper and then punch cards.  You also punched a few Job Control
Language cards.  IBM JCL was baroque in the extreme -- I remember none
of it.  After all, once you'd punched the cards to request the FORTRAN
compiler, link in whatever libraries you were using (almost all my code
used NAG numerical routines), and set up data sources and sinks, you
never typed them again; you just took them off one card deck and put
them on another.  Sometimes, if there was a run-time error, you'd
replace one card with another that requested a link map (a table showing
where code was placed in memory) so you could decode the cryptic error
message.

Once you had this card deck, you'd normally hand it to an operator, but
I was an operator so I just added it the stack that were going though
the machine's reader.  The operators (i.e. me!) picked up the fan-fold
paper output, "burst" it into separate jobs (each had a banner to
indicate the username of the job) and you put the output with the card
deck into a set of pigeon holes.

Every now and then, the job would request some resource like a magnetic
tape.  The operator would then have to go and find the right one and put
it in the tape drive.  There was some disc memory which also came in
replaceable packs, and some jobs needed to have a disc pack changed.

Sadly, it was not uncommon to wait half a day to get a print-out back
that just identified a syntax error one line 987!

This was at a university computing facility, so there were many users
running all sorts of different jobs.  Commercial set-ups were very
different.  For example, at the University it was almost never worth
saving your compiled program.  In a commercial environment the common
program would be stored, pre-compiled, on disc or tape.

I am sure there are many others here who remember this sort of
computing.  Terminals were around at the time, but they were just a
little too expensive (in terms of the computing resource they used) to
be made generally available to all university staff and students.

-- 
Ben.

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#8028

On Thu, 21 Sep 2017, Ben Bacarisse wrote:
> William Elliot <marsh@panix.com> writes:
> > On Wed, 20 Sep 2017, Ben Bacarisse wrote:
> >> William Elliot <marsh@panix.com> writes:

> >> >> >> ...  The book uses an over bar for that case: [S, S?E].
> >> >> >> 
> >> >> >> For [A, B] to be an edge cut, A ?H? B = V, A ?H? B = {}, A =/= {} and
> >> >> >> B =/= {}.
> >> >> > What does S?E and ?H? mean?
> >> >> 
> >> >> They means that some software has had trouble with the Content-Type of
> >> >> my post.  They are the transliteration chosen by that software for byte
> >> >> sequences representing a combining overline, set union and set
> >> >> intersection.
> >> >
> >> > Usenet is old fashion.  Such stuff doesn't communicate well.
> >
> > It worked much better than the new fangled stuff.
> > One example is mathstack.
> 
> Eh?  I post on Usenet because it works well -- much better than
> mathstack.

Mathstack is an example of new fangled trashiness.

> >> I prefer to think of some software as old fashioned.  With a 
> >> little help, Usenet is fit for the 21st Century.
> >
> > The new fangled stuff might work better were it designed better, 
> > standardized special characters and didn't throw in the kitchen 
> > sink, ie cram it with too much stuff.
> 
> When it comes to standards, it's inevitable that many people -- even
> most -- will be disappointed.  But it's done now and it works well
> enough.

ASCII is a good standard but MicroStuff and others refuse to use it 
with multiple character punctuation marks that appear differently with 
different readers.

> >> > We use various other plain text symbols for intersection and union.
> >> 
> >> Who is "we"?
> >
> > Those of us who wrote, learned and taught math in plain text ascii on 
> > Usenet.
> 
> Ah, right.  It's an odd word to use since I too learned that but I
> appear not to be included in the "we".

We stuck with ascii.  This discussion started with asking what strange 
byte clusters meant.

> > TeX is a hideous language to have to write.  Often writing
> > out the math in English is more proficient than writing TeX.
> >
> > I have notice that over the years, as I was forced to modernized, 
> > that my productivity has fallen for being hampered by all that new 
> > fangled stuff.  Windows as an operation system is a disaster 
> > designed for dummies who won't have to be bother learning how to 
> > use an effective operating system.  Now the computer, with mikes 
> > and cameras, is just a spy in your home.  The web is going from an 
> > excellent means of communication to a piece of commercial trash, 
> > much the same way that radio and TV has but with the added 
> > advantage of spying on you by both corporations and governments.  
> > Now under the rubric of fake news, people are being censored;  
> > left wing groups among others are targeted.  So like the radio and 
> > TV - just silly entertainment, ads and government propaganda - the 
> > web is becoming such.
> >
> > New and improved is never as good.
> 
> Oh, OK.  That's not been my experience.  My new and improved CPU is 
> way better than the one in the DG Nova I first used, and it does not 
> need cooling water like the IBM 370 either.  I much prefer to type 
> into Emacs than punch cards or tapes.  I love my delete key -- 
> re-punching cards was a royal pain, despite the handy DUP key.  In 
> fact, I don't know how we could even be having the conversation on 
> the kind of machine I started on.

Inspite of new improvements, progress progresses.
New improvements on progress has prevented us
from not destroying ourselves and everybody else.

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#8032

William Elliot <marsh@panix.com> writes:

> On Thu, 21 Sep 2017, Ben Bacarisse wrote:
>> William Elliot <marsh@panix.com> writes:
>> > On Wed, 20 Sep 2017, Ben Bacarisse wrote:
>> >> William Elliot <marsh@panix.com> writes:
>
>> >> >> >> ...  The book uses an over bar for that case: [S, S?E].
>> >> >> >> 
>> >> >> >> For [A, B] to be an edge cut, A ?H? B = V, A ?H? B = {}, A =/= {} and
>> >> >> >> B =/= {}.
>> >> >> > What does S?E and ?H? mean?
>> >> >> 
>> >> >> They means that some software has had trouble with the Content-Type of
>> >> >> my post.  They are the transliteration chosen by that software for byte
>> >> >> sequences representing a combining overline, set union and set
>> >> >> intersection.
>> >> >
>> >> > Usenet is old fashion.  Such stuff doesn't communicate well.
>> >
>> > It worked much better than the new fangled stuff.
>> > One example is mathstack.
>> 
>> Eh?  I post on Usenet because it works well -- much better than
>> mathstack.
>
> Mathstack is an example of new fangled trashiness.

Yes, I know, but I can't see the point in referencing it.  There are
examples of bad new things and of good new things.  There's no point in
referring to examples of either unless they somehow relate to the point
being discussed.

>> >> I prefer to think of some software as old fashioned.  With a 
>> >> little help, Usenet is fit for the 21st Century.
>> >
>> > The new fangled stuff might work better were it designed better, 
>> > standardized special characters and didn't throw in the kitchen 
>> > sink, ie cram it with too much stuff.
>> 
>> When it comes to standards, it's inevitable that many people -- even
>> most -- will be disappointed.  But it's done now and it works well
>> enough.
>
> ASCII is a good standard but MicroStuff and others refuse to use it 
> with multiple character punctuation marks that appear differently with 
> different readers.

Again, I not sure why you are saying this.  Some software is broken.
That's not news.

>> >> > We use various other plain text symbols for intersection and union.
>> >> 
>> >> Who is "we"?
>> >
>> > Those of us who wrote, learned and taught math in plain text ascii on 
>> > Usenet.
>> 
>> Ah, right.  It's an odd word to use since I too learned that but I
>> appear not to be included in the "we".
>
> We stuck with ascii.

I am still not included in the "we" so it's wrong to talk about "we"
having done anything.  *You* stuck with ASCII, and I hope it turns out
to be a good choice for you.

> This discussion started with asking what strange 
> byte clusters meant.

Yes, and I explained what they meant.  You can now contribute to the
discussion.  Did you have anything to say about the topic, or did you
just want to complain about the three characters you could not identify?

<snip>
-- 
Ben.

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#8033

> > This discussion started with asking what strange 
> > byte clusters meant.
> 
> Yes, and I explained what they meant.  You can now contribute to the 
> discussion.  Did you have anything to say about the topic, or did 
> you just want to complain about the three characters you could not 
> identify?

Google Groups has different standards than Usenet.
Adhering to Google Group standards means you're not 
communicating with those using Usenet.

Though I now know that it's an interesting topic, I won't be 
participating in it for the difficulty of deciphering your posts and 
the added difficulty of replying with your special characters.  Use of 
TeX, should you need fancy symbols, is much to be preferred for it's 
raw code is easy to read while non-standard, control characters 
proprietary to a company's software are meaningless.

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#8034

On 23/09/17 03:49, William Elliot wrote:
>>> This discussion started with asking what strange
>>> byte clusters meant.
>>
>> Yes, and I explained what they meant.  You can now contribute to the
>> discussion.  Did you have anything to say about the topic, or did
>> you just want to complain about the three characters you could not
>> identify?
> 
> Google Groups has different standards than Usenet.
> Adhering to Google Group standards means you're not
> communicating with those using Usenet.

Are you seriously claiming that Ben Bacarisse, of all people, uses 
Google Groups? Did you not even bother to check his headers?

> Though I now know that it's an interesting topic, I won't be
> participating in it for the difficulty of deciphering your posts and
> the added difficulty of replying with your special characters.

I have a certain sympathy with your point about non-ASCII characters, 
but not with the way you've made that point. After all, it's hardly 
/that/ difficult, in a discussion about sets, to work out that, if there 
are two characters you can't read, they are probably the union and 
interection symbols. [1]

> Use of
> TeX, should you need fancy symbols, is much to be preferred for it's
> raw code is easy to read

I found Ben's symbols easy enough to read. I am not convinced that I'd 
have found \cup and \cap quite so intuitive.

> while non-standard, control characters
> proprietary to a company's software are meaningless.

UTF-8 is proprietary? When did that happen?

William, you had a perfectly valid point about the fact that Usenet is 
supposed to be an ASCII-only medium, but you've over-cooked that point 
by mis-characterising BB as a GG user, by claiming that ASCII renditions 
of union and intersection symbols are difficult to decipher in the 
context of a discussion on set theory, by posting a spurious `solution' 
to the problem that doesn't actually work, by claiming that UTF-8 is 
non-standard and proprietary, and by banging on about it for several 
articles in a row; but *mostly* you have overcooked your point by being 
unpleasant about it. That wasn't necessary.

Let it go.



[1] Students of English are challenged to remove as many commas as 
possible from that sentence whilst, at every stage, retaining or 
improving its overall clarity.

-- 
Richard Heathfield
Email: rjh at cpax dot org dot uk
"Usenet is a strange place" - dmr 29 July 1999
Sig line 4 vacant - apply within

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#8035

Richard Heathfield <rjh@cpax.org.uk> writes:

[...]

> [...] After all, it's hardly /that/ difficult, in a discussion about
> sets, to work out that, if there are two characters you can't read,
> they are probably the union and interection symbols. [1]

[...]

> [1] Students of English are challenged to remove as many commas as
> possible from that sentence whilst, at every stage, retaining or
> improving its overall clarity.

I'm certainly not the right person to claim I have a solution here ---
as I don't know any English grammar --- but I'd just guess first that by
removing all commas there we have a perfectly grammatical phrase.  That
is,

  After all it's hardly /that/ difficult in a discussion about sets to
  work out that if there are two characters you can't read they are
  probably the union and interection symbols.

I can't say it improves clarity.  I think the commas, even if
unnecessary, are safeguards to clarity.  But I think this phrase in
particular sounds perfectly clear to me --- perhaps luckily.

Second guess:

  After all it's hardly /that/ difficult in a discussion about sets to
  work out that if there are two characters you can't read, they are
  probably the union and interection symbols.

Perhaps I shouldn't remove that last comma because we have a conditional
there implying the two sentences (1) ``if there are two [...]'' (2)
``they are probably [...]'' have a relation of subordination, that is,
the second sentence is dependent upon the first and so the comma
indicates a separation of the two.  (So we don't try to interpret it as
one ``whole'', non-subordinate sentence.)

That's my reasoning.  I couldn't back it up with grammatical reference.

In other words, I'm saying perhaps your phrase is clarified with this
this parenthesis-notation.

  After all it's hardly /that/ difficult in a discussion about sets to
  work out that (if there are two characters you can't read, they are
  probably the union and interection symbols).

That is, your phrase is

  It's hardly-difficult to work out that (X).

Since X happens to be a ``long'' subordinate phrase, so a comma is
required to organize it.

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#8042

On Saturday, September 23, 2017 at 8:04:24 AM UTC+1, Richard Heathfield wrote:
> I have a certain sympathy with your point about non-ASCII characters, 
> but not with the way you've made that point. After all, it's hardly 
> /that/ difficult, in a discussion about sets, to work out that, if there 
> are two characters you can't read, they are probably the union and 
> interection symbols. [1]

> [1] Students of English are challenged to remove as many commas as 
> possible from that sentence whilst, at every stage, retaining or 
> improving its overall clarity.

If a discussion about sets unexpectedly introduces two characters you can't read it is not difficult to work out that they are probably the union and intersection symbols.

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#8037

William Elliot <marsh@panix.com> writes:

>> > This discussion started with asking what strange 
>> > byte clusters meant.
>> 
>> Yes, and I explained what they meant.  You can now contribute to the 
>> discussion.  Did you have anything to say about the topic, or did 
>> you just want to complain about the three characters you could not 
>> identify?
>
> Google Groups has different standards than Usenet.
> Adhering to Google Group standards means you're not 
> communicating with those using Usenet.

You seem to be confused about standards.  I have no idea what you think
Google Groups has to do with this, but I refer to the RFCs for how a
Usenet post should look, and for many years now, posts may have a
Content-type: header that specifies charset=utf-8.

> Though I now know that it's an interesting topic, I won't be 
> participating in it for the difficulty of deciphering your posts and 
> the added difficulty of replying with your special characters.

Yes, I can see it might be awkward since your Usenet software appears to
hide even the fact that the characters were different.

> Use of 
> TeX, should you need fancy symbols, is much to be preferred for it's 
> raw code is easy to read while non-standard, control characters 
> proprietary to a company's software are meaningless.

I didn't use any non-standard proprietary control characters.

-- 
Ben.

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#8039

> I didn't use any non-standard proprietary control characters.

>> The book uses an over bar for that case: [S, S?~E].
>> For [A, B] to be an edge cut, A ?~H? B = V, A ?~H?

That is what is unreadable.  What you see here is was cut and 
pasted into this reply.  On the screen, ? appears as a high-bit 
blank, ~E appears as a single character, ctrl-E and ~H appears 
as a single character, ctrl-H.  What did you type to get that?

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