Node identifiers of quantifiers in EDS

What is the name for the node identifiers starting with underscore:

{e2:
 _1:udef_q<0:3>[BV x3]
 e9:card<0:3>("2"){e SF prop, TENSE untensed, MOOD indicative, PROG -, PERF -}[ARG1 x3]
 x3:_dog_n_1<4:8>{x PERS 3, NUM pl, IND +, PT pt}[]
 e2:_fight_v_1<13:21>{e SF prop, TENSE pres, MOOD indicative, PROG +, PERF -}[ARG1 x3]
}

I mean the _1 above.

What do you mean, “the name for the node identifiers”?

Do note that in EDS and DMRS, node identifiers are not variables. For convenience and at the risk of some confusion, EDS uses the form of the ARG0 variables of the MRS’s EPs for the corresponding node’s identifier, but they do not behave exactly like variables. Furthermore, they must be unique and each node must have an identifier, so for those that are missing or non-unique, they will get an underscore instead of an e, i, x, etc. Most prominently, you’ll notice this on quantifiers, which do not have their own intrinsic variables. You’ll also see these on (arguably bad) MRSs where EPs have no ARG0 or share their ARG0 with some other non-quantifier EP.

No meaning should be attributed to either the letter (or underscore) portion of the identifiers nor to the numeric portion, and neither is required. The identifier is just a unique string of valid identifier characters.

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Thank you, my original question was how do we call those variables with an underscore… but your answer was even better, now I understood where they came from during the translation from MRS to EDS.

Despite all reading about MRS variables vs EDS identifiers (constants), I still have some doubts about the difference. I understand that MRS handlers must be understood as variables, otherwise, the HCONS wouldn’t make sense, they are constraints that precisely make assertions of possible equalities. So handlers are for sure variables (in the computational and mathematical sense). But what about x or e or i MRS variables? The ICONS constraints are never really used, right? At least for some sentences, ACE didn’t give me values for the ICONS.

I am reading now http://www.lrec-conf.org/proceedings/lrec2006/pdf/364_pdf.pdf and trying to understand the variable-free motivation. Parts such as the one quoted below confused me, it seems that variables vs constraints are related to the preservation of identifiers between possible analysis of a sentence. But two distinct possible analyses aren’t two distinct MRS? If EDS is derived from MRS, it doesn’t make sense for me this quote.

the EPs associated to an NP constituent shared among two analyses might well internally end up using distinct (albeit abstractly equivalent) semantic variables.

MRS variables are logical variables. This means that they specifically stand for individuals in a model structure. As you say, handles are mathematical variables, in the sense that each handle must be equated with a label in a fully scoped MRS. However, a label/handle only ever refers to a linguistic object and never an individual in a model structure. This is really important if we want a well-defined logic, where we can have a model structure to represent a situation, and an MRS to represent a sentence, and then evaluate the MRS on the model structure.

However, for many applications, we don’t need a well-defined logic and so the logical variables can seem cumbersome. Hence the motivation for a simpler variable-free representation.

As for the specific quote, I think it refers to a situation where there are two analyses for a sentence but they share the same analysis for a particular NP. In assigning a unique identifier to each variable, the identifiers might end up being different because the analysis of the rest of the sentence is different, even though the analysis of the NP is the same. If the identifier instead comes from the token, it will be the same identifier across all analyses.