Modus Hopper Random: November 2018

Sunday 25 November 2018

Skelmersdale Almost Force a Draw at Greenfields

Hopperational Details

Date & Venue

Saturday 24 November 2018 at Greenfields Sports Ground

Result

Market Drayton Town 2 Skelmersdale United 1

Competition

Northern Premier League Division One West (Step 4)

Hopstats

This is ground number 666 on the lifetime list and I am here randomishly because of the specific symmetric properties of a cat-feeding mat that was drawn to my attention yesterday. All is covered in the preceding blogpost, and arises because I had exactly 17 grounds from which to choose. There happen to be exactly 17 distinct ways of combining elements of symmetry (such as rotation and reflection) to create a repeating pattern in two dimensions – they are known as plane symmetry groups, or “wallpaper groups”. I always wanted this blog to be "different", so there. Here’s the mat in question with rhombic unit cell, mirror lines and centres of 2-fold rotational symmetry marked up.

Many thanks to @ThrstleFantstic for playing along on Twitter yesterday, and @ianshillaker1 for another image a few moments later which became my reserve.

Context

Neither team in good form – 14^th plays 20^th.

In one sentence

The home side held on for the win after a late dismissal but they had wasted several chances earlier in the game.

So what?

MDT up to 11^th, Skelmersdale stay 20^th with a gap of four points.

Match Report

MDT took the game to their visitors in the early stages and the tone was set by Glynn Coney hurdling a flying Skelmersdale tackle and crossing the ball from the left. Daniel Beddows was arriving from midfield headed the ball firmly but wide. So it continued with plenty of home chances with the occasional visitor break. One of these needed a magnificent old-school tackle to prevent a shot on goal – and to be fair to the attacker, he took a moment to recover before just getting up and getting on with it.

MDT took the lead after 20 minutes. I was at the other end at the time, but could see that Skelmersdale keeper Terry Smith had come off his line to block an incursion into the left edge of the area but was then unable to stop an incoming shot from a wide position by Charlie Knowles. The home side were caught asleep defensively though within two minutes. On their first attack from the restart, Will Dunne scored an equaliser with a crisp shot from the edge of the area, untroubled by any challenge.

Incredibly, MDT nearly scored again immediately as Skelmersdale themselves lost concentration for a moment, but soon after, with 26 minutes on the clock, they cut through the centre of the defence to retake the lead through Jud Ellis.

My half-time note was to the effect that MDT deserved their lead but had been somewhat wasteful in front of goal and might regret that later. As it happened, there were no more goals in the second half. Knowles hit the bar, and then shot wide having been teed up by Ellis. MDT continued to press, but as the game wore on maybe they tired or started defending deeper, and Skelmersdale were definitely showing ambition for a second equaliser. It was end-to-end high-effort stuff, but both sides lacked precision in their final pass.

It also became somewhat tetchy and the card-count increased. A foul on an MDT player was loudly proclaimed from the bench as an “assault” and they had the ball in the net, but disallowed, from the resulting set-piece. With about ten minutes to go, something happened at the far end that led to raising of hands, pushing and shoving, and a delay of a few minutes. The outcome of the officials’ conference was more yellows and a red for MDT’s Lyndon Campbell.

This meant a few nervy minutes of hanging on for MDT, but they managed it. Probably a fair result overall but other clubs would be unwise to think of Skelmersdale (under relatively new management) as on their way to relegation.

Pix

Interesting ground for the hopper fraternity – all neat and tidy with clearly labelled facilities (think 1970s Batman TV series - but with a "catapostrophe" for you to spot), good views, friendly people, nice clubhouse. Well worth a Shropshire diversion even if at times the players and the dugouts between them were making all the noise. MDT in red.

Goalkeeper Top Colour Stats

New this season – a pre-match prediction based only on keeper top colours as a preliminary test of the data. Proper statistical significance test to follow in due course.

Today, as expected, Blue beats Orange. However, no clean sheets and no change in the league table positions.

Pre-match Prediction based on Keeper Top Colour:

Prediction:	Home Win
Was the prediction correct?	Yes
% of correct predictions so far	68% (15 from 22)

Based on conventional 3pts for a win, 1pt for a draw, but also -1pt for a goal conceded (GC) and +5pts for a clean sheet (CS). Colours ranked on a points per game (PPG) basis. For new readers the odd .5 was caused by a shocking half-and-half shirt and the .1 was due to a substitute goalkeeper in a different colour. The Fire Cracker colour was confirmed with the help of the social media team at Dulux UK. All of this arises from a comment attributed to Petr Cech that orange is the best colour for a goalkeeper because it changes the behaviour of other players around the box. It may not be statistically significant as yet, but football coverage ignores this point as a matter of routine.

	P	W	D	L	GC	CS	Pts	PPG
Red	10.0	5.0	1.0	4.0	11.0	3.0	20.0	2.000
Blue	41.1	19.0	7.0	15.1	57.0	14.0	77.0	1.873
Grey	48.5	23.0	10.0	15.5	79.5	14.0	69.5	1.433
Green	86.0	43.0	11.0	32.0	145.0	22.0	105.0	1.221
Fire Cracker	3.0	1.0	0.0	2.0	6.0	1.0	2.0	0.667
Maroon	5.0	2.0	1.0	2.0	9.0	1.0	3.0	0.600
Purple	19.0	8.0	3.0	8.0	41.0	5.0	11.0	0.579
Orange	42.5	13.0	8.0	21.5	80.5	6.0	-3.5	-0.082
Radioactive Bile	21.0	9.0	0.0	12.0	45.0	3.0	-3.0	-0.143
Yellow	33.0	9.0	7.0	17.0	70.0	5.0	-11.0	-0.333
Pink	17.0	5.0	5.0	7.0	35.0	1.0	-10.0	-0.588
Black	6.0	2.0	3.0	1.0	15.0	0.0	-6.0	-1.000
White	1.9	0.0	0.0	1.9	4.0	0.0	-4.0	-2.105

What Next?

Follow @GrahamYapp on Twitter! 36 Step 4 grounds left to go until I reach my next personal landmark of “The 388” (everywhere in England in the top eight tiers of the game).

Friday 23 November 2018

Good Plane Fun

For this weekend, I have exactly seventeen unvisited step 4 grounds to choose from. This is not a number that lends itself easily to random methods involving dice, coins or sports events. However, I remember from my first year Crystallography course at Cambridge (yes, really) that there are exactly seventeen different ways of organising a repetitive pattern in two dimensions. As undergraduates, we learned about the two-dimensional case before moving on to the three dimensions needed for real crystal and mineral structures. Oh yes, life was good.

The seventeen plane symmetry groups have been known for a long time – the proof that seventeen was the full set was completed early in the 20^th century, but many ancient civilisations were using them in their decorative and artistic traditions.

Today, they are also known as the “wallpaper groups”. Keep reading folks, normal groundhopping will be resumed as soon as possible.

I have organised my matches into an alphabetical list, and linked each match to one of the plane symmetry groups.

Match	Plane Symmetry Group
Atherton Coll v Widnes	p1
Belper T v Loughborough Dyn	p2
Bideford v Moneyfields	pm
Brighouse T v Lincoln U	pg
Cleethorpes T v Stocksbridge PS	cm
Colne v Colwyn Bay	pmm
Felixstowe & Walton v Witham T	pmg
Glossop NE v Trafford	pgg
Market Drayton T v Skelmersdale U	cmm
Ossett Utd v Frickley Ath	p4
Pickering T v Ramsbottom U	p4m
Pontefract Coll v Carlton T	p4g
Prescot Cables v Clitheroe	p3
Runcorn Linnets v Newcastle T	p3m1
Sevenoaks v Guernsey	p31m
Slimbridge v Winchester C	p6
Street v Blackfield & Langley	p6m

As an example, the Persian tapestry shown above is in group cm and would send me to Cleethorpes. Patterns of the group cm have no elements of rotational symmetry, but they do have parallel mirror lines in one direction. The “unit cell”, the smallest repeating unit, is a rhombus – a quadrilateral with four sides of equal length but no internal angle of 90^o (which would make it either a rectangle or a square). Other groundhopping blogs are available.

You’re still here? Oh, good. However, this Persian glazed tile of group p4m would send me to Pickering Town. It has fourfold rotation symmetry – basically meaning that the pattern looks identical when you turn it through 90^o either way. You can do this four times in a complete rotation. There are also four “mirror lines”, horizontal, vertical and both diagonals. The “unit cell” is a square.

You get the idea. Now, here’s the thing. You are all surrounded by patterns – wallpapers, tiles, table surfaces, floors and so on. Anything that covers a flat surface.

The first person to tweet me a picture of a pattern from their home or workplace (as long as they don’t mind me then adding the photo to this blog) will decide my groundhopping destination. It is 11.20 am on Friday 23 November and I am about to publish. Update and news to follow soon!

UPDATE

We have a result! Thanks to @ThrstleFantstic for this picture of a cat feeding mat, annotated to show the symmetry elements of two perpendicular mirror lines (red) within a rhombic unit cell (yellow). There is considerable twofold rotational symmetry - meaning that if you turn the pattern through 180 degrees then it looks the same. The centres of rotational symmetry are the pale blue dots.

Hopefully, it can be seen that the symmetry elements of the cat mat are the same as in this piece of Persian tapestry.

... which is in plane group cmm ...

... which is why I will be at Market Drayton Town v Skelmersdale United tomorrow. Thank you for your interest - a #keepertopcolourstats result prediction (currently around 70% accurate) will appear on Twitter at 3.00pm.

Thanks too to @ianshillaker1 for this beauty, which arrived a few minutes later and as far as I can see belongs to group p1 and therefore gives me my reserve choice of Atherton Collieries.