You'll probably get a better response from solr-users. In any case, 
posting the relevant fieldtype definition from your schema.xml and, for 
good measure, the results of a query with debugQuery on would be 
helpful. Off the top of my head, I'd say it may be a combination of not 
using index time expansion on the synonym filter (query time expansion 
on multi-word synonyms can be wonky) and a word delimiter filter that's 
configured to split on numerics, i.e. "co2" => "co", "2".

M

On 05/27/2011 07:43 AM, Thomas Dowling wrote:
> Greetings--
>
> I'm trying to flesh out my synonyms.txt file for a couple of Solr indexes,
> and I stumbled across something weird.  I added these lines to synonyms.txt:
>
> co2, carbon dioxide
> ch4, methane
>
>
> The second line worked as expected: I restarted Solr, reindexed, and could
> search ch4 and methane as synonyms of each other.
>
> The first line did something weird.  Before the change, I can get results
> for both CO2 and for "CARBON DIOXIDE" (just different results).  After the
> change, searching CO2 got zero results, as did "CARBON DIOXIDE".  So at
> least they're acting like synonyms, right?  But why in the world do they
> both stop finding hits?
>
> Pre-change:
>    CO2			225 hits
>    "CARBON DIOXIDE"	130 hits
>    CARBON DIOXIDE	1030 hits
>
> Post-change:
>    CO2			0 hits
>    "CARBON DIOXIDE"	0 hits
>    CARBON DIOXIDE	1030 hits
>
>
> Also, if I want to be able to search for Greek letters by name (alpha,
> beta, etc.), is there a better way than to use synonmyms.txt?
>
>    Δ,δ,delta
>
>
> TIA
>