2.1 The nominal declension system

For the purposes of this paper, we will follow the description of Czech inflection in Cvrček et al. (2010), a careful revision of traditional descriptions based on extensive corpus evidence. This grammar uses evidence from corpora of edited text vs. spoken corpora to document in parallel the two language standards otherwise known as ‘Literary Czech’,³ mostly used in formal writing, and ‘Common Czech’, mostly used in speech or informal contexts. These differences are only marginal in nominal declension, except in the case of the instrumental plural, as discussed below.

The Czech nominal system distinguishes four grammatical genders (masculine inanimate, masculine animate, feminine and neuter),⁴ seven cases (nominative, accusative, genitive, dative, vocative, locative, and instrumental) and two numbers (singular and plural). Nouns are divided up into declension classes which characterize distinct inflectional behaviors. Table 1 illustrates the 12 most prominent classes of Czech nouns according to Cvrček et al. (2010).⁵ The Czech grammatical tradition classifies inflectional behavior in terms of two dimensions: gender, and the morphophonological status of the noun stem as being ‘hard’ or ‘soft’ (see e.g. Naughton 2005). The hard vs. soft distinction mostly boils down to a distinction between two classes of stem-final consonants, with some exceptions. Most importantly, as Cvrček et al. (2010) note, listing nouns such as KOST ‘bone’ or STAVENÍ ‘building’ as soft, as is traditional, makes little sense: /t/ is clearly a hard consonant, and i-stem neuters do not end in a consonant: we will follow their lead and take these two inflection classes to be outside the hard/soft opposition. In addition, the traditional bipartition does not exhaust inflection class distinctions; see e.g. the distinct behavior of HOST ‘host’ and TÁTA ‘dad’ in the masculine animate, or RŮŽE ‘rose’ and KRÁDEŽ ‘theft’ in the feminine. Overall, inflection class fully determines gender (no two nouns of different genders inflect in exactly the same fashion), and correlates strongly with stem-final consonant identity, but inflection class assignment is not fully predictable from gender, morphophonology, or a combination of the two. As a result of these and other observations, the Czech inflection class system is not readily describable in terms of an inheritance tree, and is best viewed as a multiple inheritance hierarchy; see Beniamine & Bonami (submitted) for elaboration of this point.

2.2 Overabundance

Table 1 already illustrates the pervasive presence of overabundance in Czech declension, with 6 out of 14 paradigm cells having multiple forms for at least some nouns in this very small sample. It also illustrates the important fact that overabundant cells typically exploit case-number suffixes also found with non-overabundant lexemes. For instance, the dative singular of HOST has two forms, combining the inflection strategies independently found with TÁTA on the one hand (-ovi) and MOST on the other hand (-u). Finally, it is worth noting that while some cases of overabundance are inflection class dependent, overabundance is systematic in the instrumental plural: all nouns exhibit two distinct marking strategies, one of them involving the vowel /i/ (written as <y> or <i>) potentially preceded by some material, the other the sequence -ma, also potentially preceded by some material.

To get a better grasp of the importance of the phenomenon, we quantified the overall lexical prevalence of overabundance using attestations in corpus data. We used version 4 of the SYN corpus (Křen et al. 2016), a tagged and lemmatized 4.3 billion token corpus of edited text published between 1989 and 2014; see Hnátková et al. (2014) for a detailed description.⁶ Note that, this being a corpus of edited text, more informal Common Czech forms are underrepresented in the corpus, although by no means absent, as we will discuss in Section 2.4.

We proceeded as follows. First, for each paradigm cell, we collected all wordforms attested in the corpus and tagged as belonging in that cell, and we noted which lemma they correspond to and the token frequency of that wordform filling that cell of that lemma. Table 2 reports as ‘attested’ the number of lexemes that are attested at least twice in the relevant cell. Second, we used simple pattern matching to identify the casenumber suffix in each word (if any), relying on the description of exponence provided by Cvrček et al. (2010). A lexeme is counted as ‘overabundant’ in a cell if at least two wordforms are found in that cell ending in different suffixes (including the zero suffix). The proportion of overabundant lexemes among attested lexemes arguably provides a lower bound on the actual lexical prevalence of overabundance.⁷

We thus find evidence for overabundance in all paradigm cells, with a proportion of overabundant lexemes varying between 0.25% in the INS.SG and 12.17% in the INS.PL. It is also striking that overabundant lexemes number in the thousands for 8 out of 14 paradigm cells, with the lowest numbers coinciding with paradigm cells that are also the least frequently attested in the corpus (e.g. vocative is barely found in a corpus that contains little dialogue). We conclude that overabundance is overwhelmingly attested in Czech, doing away with any doubt that one would be dealing with a minor phenomenon. It might be that Czech is unusual in that respect, and that the high prevalence of overabundance is linked to the language’s particular diglossic history (see Bermel 2000 for a useful discussion). However, since to our knowledge the prevalence of overabundance has never been evaluated on a large scale for any other language at this date, there is currently no evidence to support such a claim.

With these very general observations in hand, we turn to two more specific case studies.

2.3 Hard masculine inanimate nouns in the LOC.SG

The locative singular is home to a number of overabundance phenomena. We focus our presentation on the situation of hard masculine inanimate nouns, although similar points could be made about other parts of the system, and we will present some relevant analysis in section 3. Hard masculine inanimate nouns may use two different endings in the LOC.SG: -u or -ě.⁸ Some nouns are attested with both, and are hence overabundant.⁹

In the SYN corpus we find that, among masculine inanimate nouns attested at least twice, 15959 nouns only appear with -u, 1056 only appear with -ě, and 2041 are found with both endings. Hence about 10% of the relevant nouns are undisputably overabundant. Sampling accidents may have led to finding attestations of only one of the two forms for other lexemes that are indeed overabundant: hence this 10% proportion should be taken as a lower bound to the true proportion of overabundant lexemes.

To get a better grasp of this situation of overabundance, we examine how the proportion of use of -u vs. -ě varies across lexemes. Figure 1 shows the distribution of these proportions for lexemes attested at least 100 times in the corpus in the LOC.SG,¹⁰ and at least once with each of the two exponents.

Figure 1

Histogram of the by-lexeme proportion of use of -u in the locative singular for overabundant hard masculine inanimate nouns with a token frequency of 100 or more, in the SYN corpus. Proportions of exactly 0 and exacly 1 are excluded; the first bar (resp. the last bar) hence shows the number of lexemes with strictly more than 0% and at most 1% (resp. at least 99% and strictly less than 100%).

The distribution is strikingly u-shaped: the vast majority of overabundant lexemes exhibit a strong preference for either -u or -ě. In fact, about half of the relevant lexemes are found 95% of the time or more with one of the two endings, and only 108 (about 5%) have no strong preference, with a proportion of -u between 40% and 60%.

What could be the source of this distribution? Two alternative hypotheses need to be considered. First, the corpus distribution could reflect true lexical variability: each lexeme has its own probabilistic level of preference for -u or -ě, with most lexemes exhibiting a strong preference for one or the other, whatever the cause of that preference. Alternatively, it could be that the observed distribution is a consequence of noisy data. Although we will conclude that the former is true, it is necessary to take the time to examine the latter hypothesis.

Suppose that each relevant noun truly has a single LOC.SG form, but production errors introduce a bit of random noise: sometimes a speaker will incorrectly inflect a noun with the wrong suffix. For concreteness let us assume that such errors happen 1% of the time. Under that scenario, the observed proportion of use of -u for each lexeme corresponds to a different sample of one of two underlying processes. For each of the two processes, most samples will exhibit a proportion of use of -u close to the true proportion—by hypothesis, either 1% or 99%—but a few will by chance end up containing a disproportionate proportion of the ‘wrong’ form.

Such a story is appealing, as it explains away apparent overabundance. However, it makes a clear prediction that happens to be falsified. If the hypothesis was true, then the likelihood of a lexeme being seen with a balanced distribution of forms should decrease with the frequency of the lexeme. In other words, lexemes with balanced proportions of -u or -ě should have a markedly lower frequency than lexemes on the borders. As Figure 2 shows, this is not the case: the median frequency of lexemes with a more balanced distribution is not noticeably lower than that of lexemes with an imbalanced distribution.

Figure 2

Median frequency of overabundant lexemes in the LOC.SG for different bands of proportion of -u.

In addition to this corpus evidence, Bermel & Knittl (2012a) provide experimental evidence for the same conclusion. In their experiment, speakers were asked to rate the acceptability within a series of syntactic contexts of the two locative singular forms, for nouns with different proportions of -u in a corpus. They found that the acceptability of an ending correlates positively with its proportion of use. In particular, lexemes with a balanced use of -u and -ě do not exhibit a marked preference in acceptability for one or the other ending.

Both macroscopic corpus evidence and microscopic experimental evidence thus lead us to conclude that the U-shaped distribution documented in Figure 1 reflects true lexical preferences: most overabundant lexemes have a marked preference for one or the other suffix, but some have a more balanced distribution. Note that, by saying that lexemes have lexical preferences, we do not exclude the possibility that these follow at least in part from general tendencies. The literature on Czech is replete with observations on phonological, morphological, syntactic, semantic, and sociolinguistic factors purported to have an influence—see Cummins (1995) for a review and Bermel & Knittl (2012a; b) as well as Bermel, Luďek Knittl & Russell (2015) and Bermel, Luděk Knittl & Russell (2018) for empirical evidence. In fact, the remainder of this paper will further document such conditioning. The important conclusion for the time being is that overabundance cannot be explained away as a consequence of such factors: there is a robust class of lexemes exhibiting variable inflectional behavior in the locative singular.

2.4 The instrumental plural

In Czech, all nouns may occur in two forms in the instrumental plural. Examples of both forms can be seen in (4):

As Table 1 indicates, actual endings vary quite a bit, but can always be distinguished on the basis of whether the ending contains the sequence -ma (full ending -ama, -ema, or -ma) or not (-y, -i, -ami, -emi or -mi). For simplicity we will collectively refer to those as the -ma and non-ma endings.

Cummins (2005) provides a useful overview of the historical causes of that situation, from the emergence of -ma endings in dialects of Czech in the sixteenth century (a reanalysis of an old dual ending), through its condemnation by early normative grammars and nineteenth century language revivalists, to its role in the codification of Literary Czech and Common Czech in the twentieth century. The alternation between -ma and non-ma forms is clearly sociolinguistically conditioned. The -ma form is felt as informal, unexpected in writing, and frowned upon in school; it is not listed in most resources providing declension tables, including the Internetová jazyková příučka maintained by the Czech Language Institute of the Academy of Sciences of the Czech Republic.¹¹ On the other hand, the non-ma form is felt as formal, bookish in speech, and the preferred form in schooling. Cvrček et al. (2010) labels the former as spoken forms and the latter as written forms.

The distribution of overabundant instrumental forms the SYN corpus follow the pattern that one would expect given these general observations. Remember that this is a corpus of edited text, comprising press, nonfiction books, and literature. This leads to four expectations. First, we expect -ma forms to be rare in that corpus. This is clearly borne out: the overall token frequency of -ma forms in the corpus (73,255) is two orders of magnitudes lower than than of non-ma forms (17,273,831). Second, we expect most lexemes to be found much more frequently with non-ma forms. Again, this is clearly borne out: only 3% of lexemes use the -ma form more than 1% of the time, leading to an L-shaped distribution of the proportion of use of the -ma forms, shown in Figure 3, that contrasts sharply with the U-shaped distribution found in the locative singular (see Figure 1).

Figure 3

Histogram of the by-lexeme proportion of use of -ma forms of the INS.PL for overabundant nouns with a token cell frequency of 100 or more, in the SYN corpus

Third, we expect the proportion of use of -ma forms to correlate with lexeme-level sociolinguistic properties: lexemes that are more likely to be used in an informal context are also more likely to be used in a -ma form. Testing this prediction in detail is beyond the scope of this paper. However it is striking to look at the few lexemes with more than 1000 attestations and a proportion of use of the -ma forms above 10%. Of these 11 lexemes, 5 are frequent colloquialisms (KLUK ‘boy’, HOLKA ‘girl’, CHLAP ‘man’, ŽENSKÁ ‘woman’, KÁMOŠ ‘friend’), two are polysemous terms whose relevant attestations have a colloquial secondary meaning (PRÁŠEK ‘powder’, also colloquial term for ‘pill’; KOZA ‘goat’, also colloquial term for ‘breast’), two refer to concepts overwhelmingly discussed in informal settings (CHLUP ‘body hair’, ŠKVAREK ‘greaves’), one is a false positive (SCHOD ‘step’: the vast majority of attestations of schodama are in the collocation Galerie pod schodama, litt. ‘gallery below the steps’, a fixed proper name). In the end, CHVTLKA ‘short moment’ is the only case where the higher proportion of -ma forms does not obviously relate to a lexically-conditioned restriction to informal contexts.

Fourth, we expect the proportion of use of -ma forms to correlate with textual genres. Our reference corpus gives us limited access to relevant information in the form of a broad classification of texts. The breakdown is shown in Table 3. As one might expect, literary texts gives rise by far to the highest proportion of -ma forms, as these may contain dialogue and/or writing in an informal or speech-like style. Nonfiction, which in this corpus consists mostly of academic writing, is at the other end of the spectrum. Press stands in the middle, with magazines more informal than daily newspaper.

Overall then, the broad distribution of instrumental plural forms in the corpus confirms the observations from the literature.

2.5 Summing up

After establishing that overabundance is highly prevalent in Czech nominal declension, we have focused on two particular cases that contrast in multiple dimensions. In the locative singular of hard masculine inanimate nouns, a minority of nouns are overabundant, while in the instrumental plural all nouns are overabundant. Proportions of use of the two forms in the corpus follows a U-shape for the former, and an L-shape in the latter. This is linked to the fact that the choice of form in the instrumental plural is clearly subject to sociolinguistic conditioning, while this is not obviously the case in the locative singular.

In the remainder of this paper we turn to our main topic: how does overabundance interact with inflectional classification? In section 2, we examine the predictability of overabundance: we show that, in the locative singular, the overabundant character of a noun is predictable from its stem shape and distribution, while this is not the case in the instrumental plural. In section 4, we examine the relationship between syntactic usage and overabundance: we show that overabundant locative singular nouns exhibit singular properties that are not found with their non-overabundant counterparts. Both studies lead to the conclusion that some, but not all, overabundance phenomena should be treated in terms of the postulation of a specific overabundant inflection class.

3.2 Results

3.3 Taking stock

In this section we developed a sustained argument to the effect that overabundance in the locative singular and instrumental plural interact in different ways with the inflection class system: in the locative singular, there are distinct classes of overabundant lexemes, and these classes are mixed inflection classes;¹⁶ in the instrumental plural, overabundance is orthogonal to the inflection class system, and fully conditioned by sociolinguistic factors.

The exact nature of overabundant locative singular classes remains somewhat confusing at this point: we have argued that they are first class citizens of the inflection class system, but that, in terms of class predictability, they mix and match properties of pairs of other classes. In the next section we develop an independent argument to the effect that overabundant locative singulars have properties of their own, irreducible to those of the neighboring non-overabundant classes.

4.1 Motivation

The preceding section has shown that overabundance in the locative singular integrates with the inflection class systems. In the case of hard masculine inanimate nouns, we showed that it was partially predictable on the basis of stem phonology and distribution which nouns are overabundant, and further showed that overabundant nouns occupied an intermediate space between ‘-u only’ and ‘-ě only’ nouns in terms of motivation: on average they share properties with both, which makes them easily confusable with both. We concluded that we should think of these overabundant nouns as belonging to a mixed class. We then generalized this result to other cases of overabundance in the locative singular.

In this section we explore in more detail the nature of mixed classes, and start with a quick review of relevant theoretical concepts in the literature. There is a consensus across frameworks in theoretical morphology that inflection class systems should be conceptualized as inheritance hierarchies, where classes may have different levels of specificity, and more specific subclasses inherit properties of their less specific superclasses (see among many others Corbett & Fraser 1993; Dressler & Thornton 1996; Koenig 1999; Beniamine, Bonami & Sagot 2017). Beniamine (2021) further argues that inflection class systems are best modeled as MONOTONOUS MULTIPLE INHERITANCE HIERARCHIES of the kind familiar from Head-Driven Phrase Structure Grammar (Pollard & Sag 1994).¹⁷ Under this view, class systems are not trees, but LATTICES, where a node may have more than one parent. Beniamine’s central argument rests on the existence and pervasiveness of HETEROCLITE CLASSES, which have an inflectional behavior intermediate between those of two other classes (Stump 2006).¹⁸ Czech neuter nouns of the class of KUŘE ‘chicken’ are a case in point, as illustrated in Table 16: in the singular they use the same exponents as soft nouns, while in the plural they use the same exponents as hard nouns. Importantly, although this is not the canonical situation, heteroclite nouns may also have properties of their own, not deducible from the properties of the two other relevant classes (Kaye 2015: chap. 2). Again, Czech neuter heteroclites illustrate this: the presence of the stem augments -et in some singular cells and -at in all plural cells is found with all and only neuter heteroclites.

This behavior is easily captured in a monotonous multiple inheritance hierarchy by assuming that heteroclite nouns are assigned to a MEET node in the hierarchy: a node that inherits from two parents rather than one. Bonami & Crysmann (2018) propose an analysis along exactly these lines of the Czech nominal system, within the framework of Information-based Morphology (Crysmann & Bonami 2016). The crux of their analysis is summarized in Figure 4. Here the structure of the hierarchy is represented in the center, while the dotted boxes indicate sample exponence rules that are associated with nodes in the hierarchy. Nouns like MĚSTO use -o in the nominative singular by virtue of being assigned to the strict-neu-hard-class, but also inherit from the superclass neu-hard-class the property of using -a in the plural. By contrast, nouns like MOŘE use -e in the nominative plural by virtue of being assigned to the strict-neu-soft-class, but also inherit from the superclass neu-soft- class the property of using -e in the singular. Most importantly, heteroclite nouns such as KUŘE inherit their singular exponents from the soft-class they share with strictly soft nouns, and their plural exponents from the hard-class they share with strictly hard nouns.

Figure 4

Heteroclite classes as meets in an inflection class hierarchy (Beniamine 2021; Bonami & Crysmann 2018).

Let us now come back to overabundance against this background. There are two possible conceptualizations of overabundant inflection classes, both of which have been proposed in the literature. On the one hand Bonami & Crysmann (2018: 193–198) argue that overabundant classes should be analyzed as joins in an inflection class hierarchy. This is illustrated in Figure 5. The intuition here is that overabundant lexemes belong to a class that underspecifies the distinction between the two corresponding non-overabundant classes, and is the mirror image of a heteroclite class. The way this is captured is by associating the inflection rules respectively introducing the suffixes -u and -ě to the two more specific classes, and assigning lexemes to classes as indicated in the figure. The architecture of IbM then ensures that overabundant lexemes will be compatible with both exponents, because any concrete use of an overabundant lexeme has to pick one of the subtypes of the overabundant class.¹⁹

Figure 5

Overabundant classes as joins in an inflection class hierarchy (Bonami & Crysmann 2018).

On the other hand, both Guzmán Naranjo (2019) and Beniamine (2021) propose that overabundant classes be analyzed as meets in an inflection class hierarchy. This is illustrated in Figure 6. The two authors converge on this solution for different reason. For Beniamine, this is a consequence of deriving the inflection class lattice from individual properties of exponence exhibited by lexemes using formal concept analysis (Ganter & Wille 1998): in this framework, meets represent shared features, while joins represent the absence of features. For Guzman Naranjo, it derives from the decision that meet nodes in the hierarchy inherit all inflection strategies exhibited by their parents. Note that, under this line of analysis, heteroclite and overabundant classes are both represented by meet nodes in the hierarchy, but contrast as to whether the two parents of the meet contribute complementary or competing inflectional strategies.

Figure 6

Overabundant classes as meets in an inflection class hierarchy (Guzmán Naranjo 2019; Beniamine 2021).

It is worth noting that, although they are conceptually distinct, both views of overabundant inflection classes are compatible with our observations on the motivation of mixed classes: in both cases, we expect overabundant classes to exhibit intermediate behavior between their non-overabundant counterparts, and a higher confusability between overabundant classes and the others than among non-overabundant classes.

There is however one area in which the two approaches make different predictions. Under the join approach, overabundant classes can’t have positive properties that are not to some extent shared by their single exponent counterparts. This is a consequence of the monotonous flow of information in the inheritance hierarchy: a higher node in the hierarchy can’t have properties that are not shared by its descendants. By contrast, under the meet approach, nothing precludes overabundant classes from having some idiosyncratic properties not shared by higher nodes.

In this section we document exactly one such situation: we show that prepositions governing the locative exhibit differential preferences for one or the other exponent of overabundant nouns, a behavior that is not paralleled with non-overabundant nouns. Hence overabundant nouns have irreducible properties, which is not compatible with the join approach to overabundant classes.

4.2 Hypothesis: Prepositions exhibit preferences for exponents of overabundant lexemes

In the previous sections we established that there is a class of Czech masculine inanimate nouns that can take both the -u and the -ě ending in the locative singular. From this it does not follow that the choice of one or the other is entirely free: as discussed at length by Thornton (2019b), there can be both usage and grammatical conditions on overabundance. The existence and strength of such conditions is a recurring topic in the description on the Czech locative singular, reviewed by both Cummins (1995) and Bermel & Knittl (2012a; b). While no factor or combination of factors comes close to predicting categorically which of the two exponents will be used in what context, anecdotal evidence can be found for influences of noun polysemy (different senses of a noun having different preferences) and preposition polysemy (different senses of the governing preposition leading to different preferences), as well as individual idiosyncratic preferences of particular (preposition, noun) collocations. Bermel & Knittl (2012a; b) provide more compelling evidence from corpus and judgment data that types of syntactic environments have an influence: all other things being equal, -u is most preferred where the preposition heads a locative adverbial, and least likely when it is an empty preposition governed by a verb.

Elaborating on this literature, we study collocational preferences between prepositions and case-number exponents for overabundant nouns. We start from the observation that different governing prepositions seem to have different preferences as to which locative exponent is used. Table 17 shows the distribution of the two locative singular forms of the two nouns MOST ‘bridge’ and ÚŘAD ‘office’ in the SYN corpus, when they are immediately preceded by one of the five main prepositions governing the locative: na ‘on, at’, o ‘near, about’, po ‘towards, after’, při ‘at, around’ and v ‘in’.

Three important observations are in order. First, and unsurprisingly, different lexemes have different preferences in terms of combinability with prepositions: for instance ÚŘAD ‘office’ is much more likely to be found in combination with v ‘in’ than MOST ‘bridge’. Second, proportions of use of the two variants varies widely accross lexemes (MOST has a preference for the -ě form, while ÚŘAD prefers the -u form), and across combinations of lexemes and prepositions: at one extreme, the -u for of MOST is used 6% of the time with po; at the other extreme, the -u form for ÚŘAD is used 98% of time with při. But third and most importantly for us, despite lexeme-dependent variation, there still seem to be tendencies as to which prepositions prefer to co-occur with each exponent: across these two nouns, o and při have a strong preference for -u when compared to the other three prepositions na, po and v. Our goal in this section is to establish whether such contrasts are general.

4.3 Model 1: Predicting exponent preference from preposition for overabundant nouns

To this end, we collected from the SYN corpus all 27,768,583 occurrences of a hard masculine inanimate noun in the locative singular immediately preceded by a preposition. We then tabulated how many tokens of each inflectional variant (-u vs. -ě) was found for each of the 21,830 relevant lexemes in combination with each preposition. Then, among the 1733 overabundant lexemes in the dataset, we selected for study the 481 lexemes that are attested in collocation with all five prepositions under examination.

Our goal is to establish whether the likelihood of using a locative singular in -ě vs. -u varies across governing prepositions. To approach this question we built a Bayesian binomial model using Stan (Carpenter et al. 2017; Gelman, Lee & Guo 2015) and the brms interface (Bürkner et al. 2017). The predicted variable was the proportion of use of -u among uses of a locative singular, and the predictor variable was the identity of the preposition. Figure 7 shows the conditional effects of the model, with whiskers representing 95% uncertainty intervals; the fact that the whiskers are barely distinguishable shows these intervals to be very narrow and hence uncertainty very low.

Figure 7

Conditional effects of preposition on proportion of use of -u for overabundant lexemes.

The model very confidently establishes that each preposition has specific preferences: despite variability among noun lexemes, at the level of the system it is very clear that the -u form is more likely to be used in combination with o and při, while -ě is more likely to be used in combination with na, po and v.²⁰

This result indicates that overabundant nouns exhibit properties that can only be found with such nouns: by definition, non-overabundant nouns use only one form, and hence cannot exhibit differential exponence properties in combination with different prepositions.

4.4 Model 2: Predicting preposition preference from locative singular exponent

It is tempting to see the differential collocational preferences we just documented as a property characterizing the class of overabundant nouns. Before reaching such a conclusion, however, we must eliminate an alternative hypothesis. Above we have reasoned in terms of properties of overabundant lexemes, as opposed to the individual wordforms that realize these lexemes. But it is conceivable that the observed behavior is a consequence of collocational preferences linking prepositions and the individual locative singular exponents -ě and -u: perhaps the preposition v is more likely to be collocated with a -ě form than a -u form, irrespective of whether that form belongs to an overabundant lexeme or not. To test for that possibility, we need to examine how likely one is to use each preposition, depending on both the identity of the exponent and whether the lexeme is overabundant or not.

To address this question, we sampled from the dataset described in the previous subsection 400 locative singular noun forms: 100 nouns from the ‘-u only’ class, 100 nouns from the ‘-ě only’ class, 100 -u forms of overabundant nouns, and 100 -ě forms of overabundant nouns.²¹ We then built a Bayesian multinomial model predicting proportion of use of each of the five prepositions from the class of nouns. Figure 8 reports the conditional effects of the model, with each subplot corresponding to one of the subclasses of nouns.

Figure 8

Conditional effects of exponent and overabundance on proportion of use of five prepositions.

Observation of the conditional effects suggests the existence of various tendencies grouping the data in both relevant dimensions. On the one hand, the proportion of collocation with three prepositions (o, po and při) is higher for -u nouns than for -ě nouns, irrespective of whether we are talking about one of the two forms of an overabundant lexeme or the only form of a non-overabundant one. On the other hand, overabundant nouns exhibit a a more or less balanced propensity to combine with na and v, while non-overabundant ones have a marked preference for v.

Although making sense of the details of the distribution is well beyond the scope of this paper, this model clearly establishes that collocation preferences with prepositions are partially predicted by the overabundant or non-overabundant character of the noun, and cannot be solely reduced to preferences of collocation with locative singular exponents.

4.5 Discussion

At the beginning of this section we set out to establish whether mixed classes such as that of overabundant hard masculine inanimate nouns should be conceptualized as meets or joins in the inflection class systems. Under the first hypothesis, the mixed class is the superclass of two non-overabundant classes, and should hence exhibit underspecified characteristics: its properties are the disjunction of properties of the non-overabundant classes. Under the second hypothesis, mixed classes share a parent with each of the non-overabundant classes. As such, they will exhibit some properties in common with each of their sister classes, but may also have properties of their own.

We then presented evidence for the existence of such properties specific to mixed classes. We documented differential collocational preferences between exponents of locative singular and governing prepositions, and showed these not to be reducible to a more general preference of prepositions for one or the other exponent which would also manifest itself for non-overabundant classes: for instance, although the -u form of overabundant nouns is barely ever used with v, -u only nouns show no sign of reluctance to combine with v. This behavior provides an argument for conceptualizing mixed classes as joins. Irrespective of whether one sees the relevant collocational requirements as following from selectional requirements of the preposition, as reverse-selection of the governor by its governee (Bonami 2015), or as a non-directional phenomenon, the statement of these requirements needs to reference the class of overabundant lexemes without the relevant property being inherited by their non-overabundant counterparts. This is precisely what is allowed by seeing the mixed class as a join node descending from the non-mixed classes rather than a meet node with the non-mixed classes as descendents. In this instance, external motivation, in the form of collocational preferences, provides crucial evidence for the proper internal organization of the inflectional system.