Agent, Theme, counter-Theme, Partner · Finnish cloth · working claim, revisable
vaihtaa · Agent (subject) + Theme (object: partitive, or a total object) + counter-Theme (illative, X Y:hyn ‘exchange X for Y’)
Change-into · translative -ksi on that second phrase · X Y:ksi
Partner · postposition kanssa + genitive · jonkun kanssa · a pronoun can sit in the possessive suffix on kanssa (hänen kanssaan, kanssani)
Reciprocal · a plural subject with no extra marker · kesken + genitive on the participle line · adverb keskenään ‘with each other’
vaihdella · sense 1 of the dictionary is vaihtaa often or now and then · partitive object in the stamp line · vaihtokauppa is a noun
An exchange, on this reading, has someone who gives a thing and receives another, and a partner when a line names one. Kielitoimiston sanakirja’s third sense of vaihtaa is antaa jtak (omistamaansa) toiselle ja saada tilalle jtak muuta, with a cross-reference to the noun vaihtokauppa. The citation of that sense is Vaihtoi sähköurut pianoon: the organs are the thing given, and pianoon is the illative of the thing received. The partner, in the same sense, is kanssa: Vaihtaa postimerkkejä kirjeystävän kanssa.
Where the best translation diverges from English exchange. The English stub, and the Cambridge patterns the Polish page cites, keep for on the thing received and with on the partner: exchange X for Y with Z. Polish wymienić splits those with na plus accusative and z plus instrumental. Turkish değiştirmek does not split them: one suffix, -(y)lA / ile, covers the thing received and the partner, and a dative on the second phrase is the change-into sense. Finnish splits them, and the thing received is not a for-type marker. It is the illative, which Iso suomen kielioppi (VISK) §1235 calls a tulosija, a goal case: movement into a place, a state, or someone’s keeping. pianoon wears that case. The change-into reading is a different case again, the translative -ksi. The partner is neither of those cases. It is the postposition kanssa with a genitive complement.
The Theme is the object, partitive or total object. VISK §925: the object’s case varies among partitive, genitive, nominative, and accusative. The central cut is partitive against the total object. The total object’s singular form is the n-form, which this grammar calls genitive, and which the older name recorded in the same paragraph calls accusative. The plural total object has the nominative shape. The t-accusative is only the personal-pronoun form (sinut in VISK’s table) and is not in the vaihtaa lines read here. VISK §930 states the choice in aspectual terms: in an affirmative clause the partitive can be motivated by unbounded aspect or by a quantitatively indefinite NP, and otherwise the object is a total object. The dictionary prints both shapes side by side on sense 1: Vaihtaa vaatteita, vaatteet. Sense 3, the exchange, uses the same object cases: partitive postimerkkejä, tontteja, matkavaluuttaa, and the plural total object sähköurut, kolikot. This page records that case alternation as the grammar describes it.
Illative is the received thing. Vaihtoi sähköurut pianoon puts the organs in the plural total object and the piano in the illative. The head definition of sense 3 is giving something one owns and getting something else in its place. VISK §1235’s illative is the goal case in the pair with the allative. The schema vaihtaa X Y:hyn is that frame. No citation in the article adds kanssa to pianoon.
Translative -ksi is the change-into reading. VISK §1259: the translative is a directional case in change-of-state forms, and it says what someone or something becomes. VISK §978: in a transitive clause a translative adverbial characterizes the object’s referent, including a result expression. The dictionary prints Vaihtaa omaisuutensa rahaksi and Vaihtaa tuhat euroa dollareiksi. rahaksi and dollareiksi are translative. On the coin line the article prints both endings: Vaihtaa kolikot seteliksi, seteliin. seteliksi is translative. seteliin is illative. The money sense is where the two cases sit side by side. The barter citation pianoon is illative only.
kanssa plus the genitive is the partner. VISK §687: an adposition’s complement is generally genitive or partitive, and a bare possessive suffix is the equivalent of a genitive complement (kanssamme). VISK §992: Maija tulee Matin kanssa presents the second party in a modifier, genitive plus kanssa. The exchange article prints kirjeystävän kanssa, jkn kanssa, and toisen kanssa. Sense 4, exchanging words, prints hänen kanssaan: genitive hänen and the possessive suffix on the postposition. VISK §691’s kanssani is that suffix standing as the complement. The genitive is the partner’s case. It is not the case of the thing received.
Reciprocal vaihtaa keskenään, and the plural subject. The article’s reciprocal goods line has a plural subject and a partitive object and no partner phrase: Kaupunki ja valtio vaihtoivat omistamiaan tontteja. Joukkueet vaihtoivat puolta is the same shape. Sense 4’s participle has kesken plus the genitive: Virastojen kesken asiasta vaihdetut kirjelmät. The adverb keskenään is a separate entry, glossed toistensa kanssa. The article of vaihtaa does not print keskenään. The noun vaihtokauppa does, in a figurative line: Puolueiden keskenään käymä vaihtokauppa viroista. A clause vaihtaa jotakin keskenään is constructed below from the adverb’s gloss and from the plural-subject frame.
Money, vaihdella, and the noun vaihtokauppa. Sense 3a is buying and selling currency. The quantity question takes a partitive: Paljonko vaihdoit matkavaluuttaa? The ‘into dollars’ line is translative, dollareiksi. Sense 3b is giving or getting smaller or larger notes for a sum: Vaihtaa sataeuronen kahtia, pienemmäksi, and the coin line with both seteliksi and seteliin. vaihdella sense 1 is defined as vaihtaa (usein, silloin tällöin). Its stamp example is partitive only: Vaihdella postimerkkejä. The noun vaihtokauppa is kauppa jossa hyödyke vars. rahaa käyttämättä vaihdetaan toiseen. toiseen is illative, inside the definition of the noun. The noun is context for sense 3. It is not a second verb.