Regex for Finding Non-Radioactive Elements

Find the shortest regex that matches all non-radioactive elements and nothing else in the Periodic Table of Elements. This is the inverse of Regex for Finding Radioactive Elements

Radioactive Elements

'Technetium','Promethium','Polonium','Astatine','Radon','Francium','Radium','Actinium','Thorium','Protactinium','Uranium','Neptunium','Plutonium','Americium','Curium','Berkelium','Californium','Einsteinium','Fermium','Mendelevium','Nobelium','Lawrencium','Rutherfordium','Dubnium','Seaborgium','Bohrium','Hassium','Meitnerium','Darmstadtium','Roentgenium','Copernicium','Ununtrium','Flerovium','Ununpentium','Livermorium','Ununseptium','Ununoctium'

Non-radioactive Elements

'Hydrogen','Helium','Lithium','Beryllium','Boron','Carbon','Nitrogen','Oxygen','Fluorine','Neon','Sodium','Magnesium','Aluminium','Silicon','Phosphorus','Sulphur','Chlorine','Argon','Potassium','Calcium','Scandium','Titanium','Vanadium','Chromium','Manganese','Iron','Cobalt','Nickel','Copper','Zinc','Gallium','Germanium','Arsenic','Selenium','Bromine','Krypton','Rubidium','Strontium','Yttrium','Zirconium','Niobium','Molybdenum','Ruthenium','Rhodium','Palladium','Silver','Cadmium','Indium','Tin','Antimony','Tellurium','Iodine','Xenon','Caesium','Barium','Lanthanum','Cerium','Praseodymium','Neodymium','Samarium','Europium','Gadolinium','Terbium','Dysprosium','Holmium','Erbium','Thulium','Ytterbium','Lutetium','Hafnium','Tantalum','Tungsten','Rhenium','Osmium','Iridium','Platinum','Gold','Mercury','Thallium','Lead','Bismuth'

Scored by character count in the regex.
Use standard Perl regex (just no specialized functions).
Assume all lower case.
You only need to count the characters of the regex itself.

Note if you used a program to get you started and maybe post how well it did. I'll post my best attempt as an answer to get started/show an example.

Edit: Apparently Bismuth is radioactive, but since I'm assuming the universe would die from heat death before it was ever much of a problem I'm not going to worry about it now.

qw3n

Posted 2014-01-08T21:40:21.263

Reputation: 733

In addition to your other question, I also ran this through Peter Norvig's Regex Golf solver, but it spat out a 99 character solution. Sometimes humans come out on top. – EMBLEM – 2015-03-07T23:13:46.533

Nitpick: Bismuth is technically radioactive, although its decay rate is so vanishingly low that it can be treated as stable for all practical purposes.

– Ilmari Karonen – 2014-01-10T01:24:31.583

@IlmariKaronen Interesting didn't know that. I copied the lists from the internet and you know how reliable that is ;). – qw3n – 2014-01-10T01:47:44.450

I don't think the question is well specified. My understanding of "the shortest regex that matches all non-radioactive elements and nothing else" is that the string "y" shouldn't match since "y" isn't the name of a non-radioactive element; but both the solutions currently posted match "y"; effectively they do substring matches. My understanding of the question would be that the answer should be the shortest string representing a regular expression that is equivalent to the regular expression 'Hydrogen|Helium|...|Bismuth' (ie. the RE formed by joining the names of all non-radioactive elements w – None – 2014-01-10T02:47:15.760

Answers

Small improvement on qw3n's solution (93 characters):

y|^v|h.[lfdn]|[^te]i[rodnts]|[lp].t[^o]|ru?[bs]|ll|^..ro|^[^r][^u].{1,4}$|ca..i|ma|s.l|tan|gs

Basically got rid of ^t[^eh] (7 characters) clause and replaced with tan|gs (6 characters). Also I count qw3n's solution as 94 characters, not 95.

dr jimbob

Posted 2014-01-08T21:40:21.263

Reputation: 336

Character count 94

y|^v|h.[lfdn]|^t[^eh]|[^te]i[rodnts]|[lp].t[^o]|ru?[bs]|ll|^..ro|^[^r][^u].{1,4}$|ca..i|ma|s.l

qw3n

Posted 2014-01-08T21:40:21.263

Reputation: 733

What language is this? – Timtech – 2014-01-08T22:17:24.730

1@Timtech javascript's regex – qw3n – 2014-01-08T22:34:33.503

I was tempted (and am still debating internally) to vote to close this as a duplicate of your other regex golf question on the basis that the optimal solutions are within a constant of each other, as witness:

70 chars

^(?!no|c?u|ra|.*(e.[kht]|[^l][gecv]i|[^c]oh?[rn]iu|f.r|ac|sta|bn|has))

Peter Taylor

Posted 2014-01-08T21:40:21.263

Reputation: 41 901

I see your point, and in the back of my mind I had thought of this. What if there was the restriction it needed to be solved without using a global not? – qw3n – 2014-01-10T16:51:38.217

1@qw3n, that has two problems. Firstly, as a general rule if you need to prohibit the best option it indicates a weakness in the question. Secondly, it could potentially kill a better solution which casts a fairly wide net and needs to exclude a couple of cases. – Peter Taylor – 2014-01-10T17:00:46.607

When solving the general problem I went from both directions to see what the results would be. This regex was unique from the other and a unique challenge to create, but yes it ignores the fact you can use the shorter regex by adding not. But that was the reason I posted both. I thought it would be a unique challenge from the other one. – qw3n – 2014-01-10T17:15:38.937