@Theo Okay, finally got 0(0|11*00)*(ε|11*|11*0)

Note that the last union operation includes the empty string

do we need the empty string there?

Yes, in case the string doesn't end with 11* or 11*0

You can omit the epsilon if you'd like

Thanks @DavidReed :)

Or expand out the regex into 0(0|11*00)*|0(0|11*00)*11*|0(0|11*00)*11*0

ahh gotcha, thanks so much!

Yeah, ended up having to design an FSM and do manual state reduction

@alan2here Have to warn you though...they can be mean. Typical comp-sci nerd I know everything narcissism

In computer-regex, it could also be written 0(0|1+00)*(1+0?)?

and im assuming this is much more difficult to get a regex for

@Theo gimme a few minutes

Is w 0- or 1-indexed?

Although I guess it doesn't really matter

w $\in$ {0, 1}

As in, is the first position odd or even

i'm not too sure what you mean by 0- or 1-indexed

first position is odd

Okay

This is definitely possible

@DavidReed Including relevant greek mythology?

@LegionMammal978 how?

@Theo I've already finished designing the state machine

@LegionMammal978 i tried doing (01)*(10)*(0)* but that leaves for an empty string

@Theo An empty string should be allowed

But that particular regex matches stuff like 0110

@Narcissusjewel Intellectual narcissism. Greek would be closer to somatic narcissism I believe.

@DavidReed I was just trying to make myself relevant, you know how we are ;).

hahaha.Well now you're relevant! Tell me what motivated that name.

@LegionMammal978 how did you do it then?

@Theo As I said, FSM state reduction

I have a regex now, currently simplifying it as much as I can

okay

@Theo Okay, got 0*|1|01(01)*(ε|0)|10(10)*(ε|1)

It has 4 cases: 0000..., 1, 0101..., and 1010...

is 1 a case

?

I thought 0 had to be in the string

whether in even position, odd, or both

Whoops, slightly misinterpreted the language specification

Just remove that case, then

Although I suppose "all even positions are 0" could be considered vacuously true due to there being no even positions

Same with the empty string (to remove that you'd change the first case to 00*)

00*|1|01(01)*(ε|0)|10(10)*

we'd end up with this then