From: crj10@phx.cam.ac.uk (Clive Jones)
Subject: Re: Reverse Mornington Crescent
Telephone-Messages: +44 223 33 4900
Address: Christ's College, Cambridge CB2 3BU, ENGLAND.
Organization: Cambridge University Computer Laboratory
Date: Thu, 28 Jan 1993 16:49:57 GMT

In article <1993Jan28.115626.29240@infodev.cam.ac.uk> gdb15@cl.cam.ac.uk writes:
>In article <C1JLMM.588@sunlab1.bath.ac.uk> py1djf@sunlab1.bath.ac.uk (D J Ford) writes:
>>Im afraid i'm a little confused on this point, are you talking about 
>>Wilson Defence that was used in the MC World Championships in Helsinky,
>>1973, or the old Raj  champion, Brig. Gen. Massington-Thorpe, whose
>>famous defense (named after his batman) was used at Trinity College
>>Cambridge, against the Oxbridge champion JPH Henderson, MA, in a grudge
>>match in 1904 ?
>
>I've never heard of the 1904 one!  My definition of Wilson's Defence
>is "any northward move employing the triangle rule that's not
>constrained by lateral blocking" (in this case the final condition
>is of course redundant).

The two are *not* actually different. They are merely different
wordings of the same ploy. The version Guy gives above is a useful way
to think of it when constrained on the City branch of the Northern
Line, if Borowicz Exchanges on the Circle Line are not possible -
indeed, it's almost the only way to avoid losing. The reasons *why* it
stops you losing are obscure, to say the least - I've seen a proof,
somewhere, but certainly can't remember it now! I just believe that it
works.

Now, the alternative representations of the defence are:

2) A _northing_ (note, not "northward") move that hops more than one
blocking intersection, by use of a triple-interchanging pair of lines.

In this form, the defence is invaluable now that the Picadilly Line
and Victoria Line interchange thrice. It has rendered the Leicester
Square Gambit, so adored in the sixties, totally useless. As a result,
this version is never actually played - the threat of playing it is
normally sufficient.

3) A northwards move to a terminus, subject to (but not overriding)
lateral blocking.

This move may not seem strong - but it can get you out of real
trouble. Consider, for example, with Hammersmith and City laterally
blocked by previous plays:
  P1: Regent's Park
  P2: Charing Cross
  P1: Farringdon
Now, P2 is in *real* trouble. Normally, Stanmore, for example, would
normally be a *very* foolish move, but in this case, it is one of the
best (least bad) available. Wilson's Defence, as a good rule of thumb,
implies that to play Stanmore would give you a good chance of survival
from here, and, sure enough, it does. Work it out for yourself
sometime!

This is the variant played in the 1904 game. I'm not surprised that
Guy is unaware of it - since we (Cambridge) lost very badly, it has
been hushed up a little around here. I learned Mornington Crescent
before arriving, however, and thus heard about that game in other
circles.

>There's no road called "The Embankment" -- can I assume you mean
>Victoria Embankment?

Oooh - no. You certainly cannot assume he means that! "The Embankment"
has, in the past, been the name of "Embankment" station. By the tardis
rules, we have to allow this as an alternative name, which a)
circumvents the "one-word-name" rule, and b) Fixes us to before the
date of the Victoria Line for the forseeable future.

So. Dave appears to have the advantage on us. However, I think we can
recover.

Clive Jones	: British Museum STATION

Dave Ford	: The Embankment
Guy Barry	: Gloucester Road
Clive Jones	: Windsor
Guy Barry	: Verney Junction
Clive Jones	: Great Portland Street
Guy Barry	: Hammersmith Broadway
Clive Jones	: Archway
Guy Barry	: Charing Cross (Embankment)
Clive Jones	: Blake Hall
Graeme Hodgson	: Lancaster Gate 
John Farrell	: Downing Street 
Guy Barry	: Mornington Crescent 

I make it clear here that I am playing the station, not the location.
This station used to lie on the Central Line by St. Paul's, if my
memory serves me right. As a result, we have locked the Monument-Bank
escalator link out, as it had not been constructed by then. This
*should* leave us safe.

--Clive.