Can someone help me analyze this sentence and identify the sentence pattern?
The hardness / of the peanut butter / is / proportional / to the softness /of the bread.
Since the linking verb to be is used in this sentence, there can be no direct object. "proportional" is what is referred to as a predicate adjective in the position of a predicate nominative, which is what a noun is if it follows a linking verb. So, if one were to diagram this sentence in the conventional manner, one would write
[subject + linking verb+predicate adjective]
\__ butter___ \_________softness___
\the \the \of
"of the butter" is a prepositional phrase that modifies "hardness."
"of the softness" is a prepositional phrase that modifies "proportional."
"of the bread" is a prepositional phrase that modifies "softness."
The three prepositions "of" suspend from under the noun which goes on a horizontal line. The articles "the" should be on slanting lines under each of the noun objects of the 3 prepositional phrases (i.e. "butter," "softness," and "bread")
Grammarians have agreed for a long time that it is hard to agree on sentence analysis. There are many consideration, many options, and many approaches. For example, sentences may be analyzed from a morphological approach in which analysis rests with the morphemes, such as derivatives like -ies or -'s. Sentences may also be analyzed from a semantic approach in which sentence analysis rests with context or position, such as whether a word, phrase, or clause fills a given slot or performs a given function. It might be good to note that there are even differences in sentence analysis between how American grammarians or students of grammar analyze sentences and how British counterparts do.
Looked at through syntactical analysis, your sentence, "The hardness of the peanut butter is proportional to the softness of the bread," states that something is something else. In this structure is performs the function of a cupola verb that links the Subject to its Complement forming a pattern that is SVC: Subject Verb Complement of Subject. The cupola is followed by the adjective proportional, which gives added information about the Subject and is thus the Complement.
Complement slots may be filled by (1) a noun phrase, (2) an adjective phrase, or (3) a preposition phrase. In your sentence, proportional is the headword of an adjective phrase in predicative position as the Complement of the Subject. The adjective proportional is followed by a modifying prepositional phrase, which itself is modified by a second prepositional phrase. The head adjective proportional is modified by the prepositional phrase "to the softness of the bread." The noun softness (adj. soft + noun forming -ness) in the prepositional phrase is itself modified by the prepositional phrase "of the bread."
The Subject comprises the noun phrase "The hardness of the peanut butter". In this phrase, the is a determiner preceding the head noun hardness (as with softness, adj. hard + noun forming -ness). The head noun is modified by the prepositional phrase "of the peanut butter." This is modified in the same fashion that the noun softness in the Complement adjective phrase is modified by the prepositional phrase "of the bread".
The hardness of the peanut butter (S) is (V) proportional to the softness of the bread. (C)
The hardness (NP; S) of the peanut butter (PrepP modifier of hardness) is (V) proportional (Adj.; C) [to the softness (PrepP modifier of adj. proportional) of the bread (PrepP modifier of bread)].
This fits your original: The hardness (NP; S) / of the peanut butter (PrepP) / is (V) / proportional (Adj.; C) / [to the softness (PrepP) /of the bread. (PrepP)]
[Analysis according to Tagmemics Linguistics as presented by Howard Johnson, Ph.D., in Grammar and Vocabulary; Routledge Press.]
On second thought, I'm wondering if "is proportional to" might work as a verb (lke the one-word verbs "determines" or "counters"), making the sentence: Subject - Verb (VT) - Direct Object.
This approach might make better sense than trying to put an adverb of manner after a "be" verb.
I am usually pretty good at analyzing the grammar of sentences (I teach this very subject at least once a year!), but I have to admit that I am having a hard time with this sentence because of the words “proportional to” and the slash that you have placed between those words. I would be inclined to keep those words together, calling them a preposition. Here is how I would break up the sentence:
The hardness / of the peanut butter / is / proportional to / the softness / of the bread.
I am certain that “the hardness” is the subject and that “of the peanut butter” is a genitive construction (which is much like but not identical to the possessive) modifying “the hardness.” The main verb is “is”; the verb is in the present indicative, and it (the verb “be”) is likely to act as either a linking verb or an intransitive verb). So far, in other words, the sentence pattern is S V (or subject-verb).
“The softness” is just like “the hardness”; it is a noun phrase that is followed by a genitive construction (“of the bread”). That makes “the softness of the bread” a noun phrase.
I am inclined to see “proportional to” as a preposition, making “the softness of the bread” the object of the prepositional phrase, but I am less certain here.
In the end, I think that the sentence may be said to follow this pattern:
S – VI – Adverb
If so, the verb “is” must be acting as a intransitive verb (not a linking verb), and we have to accept that “proportional to the softness of the bread” is a prepositional phrase that functions as an adverb of manner (explaining how).
Maybe someone else can provide another way of analyzing the sentence.