From school grammars down to scientific writings and formal frameworks, the Czech grammars are based on syntactic dependency. This approach, which has historical roots, has been also applied in the structural theory of the Prague Linguistic Circle among whose significant members there was the French linguist Lucien Tesniere. Recently, a formal representation of the dependency structure is a rooted tree (a graph with exactly one path connecting any two of its nodes), the root of which is the predicate of the main clause, all other nodes depending each on one head. Two orderings are defined on the set of nodes: (i) the structural relation between a mother node and a daughter node, interpreted as syntactic dependency (subordination, determination), and (ii) the linear oder of meaningful word forms from the left to the right, reflecting the "underlying" word order. For further syntactic relations (coordination, apposition, parenthesis) it is necessary to work with more than two dimensions.
In a dependency based grammar the verb is understood as the centre of the sentence, which together with its arguments (constitutive valency items) constitutes basic sentence patterns (in which of course also deeper embedded items play their role: in Vítat hosty bylo zábavné 'To welcome guests was amusing' the word hosty is obligatory). Derived patterns also contain free complementations and coordinated or similar structures. Function words (prepositions, conjunctions, auxiliary verbs) are not treated as corresponding to specific nodes in the dependency tree, but rather as taking part in the function of the corresponding lexical word. Subordinated clauses are handled as sentence parts dependent on the verb or on another word.
Among the constitutive dependents of a verb (predicate) there are five arguments (each of which occurs at most once with a head verb): Actor, Patient, Addressee, Effect, Origin. Arguments other than Actor are governed by the verb (in that their morphemic form, case and/or preposition, or conjunction is determined). Actor has a special position: in an active clause it corresponds to Subject, constituting a predicative relation with the verb, which agrees with its Subject in gender and number (agreement with a coordinated or pronominal subject presents also quite complicated situations). The relation of a Patient (Direct Object) to the verb is expressed by government ('rection'): usually the Object has a form of the Accusative case, but certain verbs take Genitive (e.g. bát se koho/čeho 'be afraid of so./sth.), Dative (důvěřovat komu 'trust in so.'), or a prepositional case (myslet na 'think of', mluvit o 'speak about').
Also obligatory adverbials belong to the valency frame of a verb; they either are obligatory also in the morphemic form of the clause (e.g. Turisté směřují do hlavního města 'Tourists come to the capital', Dívka zůstala ve škole 'The girl remained at school', Schůze trvala dlouho 'The session lasted long'), or are deletable, cf. Přátelé přijeli (sem/tam) 'The friends came here/there', Odjeli (odtud/odtamtud) 'They left here/there' - here also the subject pronoun is absent on the surface; Czech is a 'pro-drop' language, in which the subject pronoun on 'he' has a zero form (also in Feminine, Plural, etc.).Free quote
The syntactic dependency of adverbials on their head is expressed neither by agreement nor by government; their form is determined by the semantics of the relationship (cf. esp. the section on Morphology, Functions of Cases). In the Czech syntactic tradition the (predicative) Complement is distinguished as dependent on the verb, but corresponding also to an 'underlying' secondary predication and standing in a close relationship to Subject or to another noun in the clause (agreeing with it in gender, number and case), e.g. Chlapec běhá bos 'The boy is running bare-footed' (agreement with Subject), Našli dědečka nemocného 'They found grandpa sick' (agreement with Object, Patient).
The valency positions can be occupied also by an infinitive or a subordinated finite verb clause (Rozhodl se odejít/že odejde/k odchodu - lit.: 'He decided to leave/that he would leave/for leaving); in some cases the verb is the only possibility (a noun is excluded, cf. Hodlal přijít dnes 'He intended to come here today', Domníval se, že jsou doma 'He believed they were at home').
The congruent adjectival adjunct is one of the dependents; it agrees with its head noun in gender, number and case, prototypically it precedes the noun. Also a non-congruent adjunct (a noun) depends on a noun; it most often has a form of the Genitive case, but other cases (with or without a preposition) are also possible, e.g. dopis matce or pro matku 'a letter to/for mother', průchod dvorem 'a passage through the yard' (one of the more specific types is the so-called Nominative of Identity: město Praha 'the city (of) Prague', klub Slavia 'club Slavia'); an adjunct of this type usually follows its head noun, and retains its own form, without agreement with the head; if a noun is accompanied by more than one non-congruent adjunct, then the first of them is the Genitive (e.g.ošetření pacienta lékařem 'the treatment of the pacient by a doctor').