I have the following two sentences:

  1. In Germany, the most common type are air-water heat pumps, followed by brine-water heat pumps.

  2. In this thesis three type(s) of optimization approaches are developed. The first type are heuristic algorithms

Is this correct or do I have to use the plural form 'types' in this context? I'd appreciate every comment.

Regarding sentence 2):

I developed three different types of optimization approaches and for each type I have multiple algorithms. For example: The first types of optimization approaches are heuristic algorithms. I have not only developed one but many heuristic algorithms.

So here is more information: I have developed 3 type(s) of optimization approaches. The first type(s) are heuristic algorithms. Here I have developed 3 methods. The second type(s) are exact methods. Here I have developed 2 methods. And the third type(s) are rule-based methods. Here I have developed 4 methods. So overall I have:

Type 1 (Heuristic Algorithms): Heuristic Algorithm 1, Heuristic algorithms 2, Heuristic Algorithm 3

Type 2 (Exact methods): Exact method 1, Exact methods 2

Type 3 (Rule-based methods): Rule-based method 1, Rule-based method 2, Rule-based mehtod 3, Rule-based method 4

So I think I should use the plural form 'types' with the plural form of the verbs 'are' and plural form of the object 'algorithms'. Is that correct?

Can someone please open the question again. I would like to give bountry for the question.

  • Comments are not for extended discussion; this conversation has been moved to chat.
    – tchrist
    Apr 19, 2020 at 16:28
  • By the way: the question has not been answered in the two linked post. My question is not whether a singular or plural verb shoud come after type. My question is if type itself should be singular or plural
    – PeterBe
    Apr 19, 2020 at 16:59
  • I do not at all understand why this quesiton is closed. I already said it quite early that the linked discussion DO NOT answer my question.
    – PeterBe
    Apr 19, 2020 at 17:03
  • A dictionary, or common sense, could tell you that one type is singular but three types is plural. A verb only ever agrees with its subject and never with the predicate complement in a copula. It is always ungrammatical to say *This type are red, blue, and green. Comments are not the place for discussion. You have a chatroom for that. It's also not the place to argue for a closed question to be reöpned. That's what our Meta site is for.
    – tchrist
    Apr 19, 2020 at 18:31
  • Thanks for your answer. I understand that I have to use the plural in the first part of sentence 2):"In this thesis three types of optimization approaches are developed"But what about the second part of sentence 2 "The first type(s) are heuristic algorithms". I'd appreciate every comment.
    – PeterBe
    Apr 19, 2020 at 18:35

1 Answer 1


I think that the correct way to say this is:

In Germany, the most common types are air-water heat pumps, followed by brine-water heat pumps.

The first type is heuristic algorithms

  • Thanks for your answer Stratos. I understand the 1. sentence. But I do not really understand why I have to use singular in the 2. sentence. Maybe I should have added that I write before 'The types of algorithms are developed in this thesis. The first types are heuristic algorithms'. Writing 'The first type is heuristic algorithms' sound strange to me (but I might be wrong), because algorithms is in plural.
    – PeterBe
    Apr 14, 2020 at 13:28
  • You say "the first type is" because "type" is singular. It doesn't matter if the type you're referring to is singular or plural, it is all one type.
    – JRodge01
    Apr 14, 2020 at 13:46
  • Thanks JRodge01 for your comment. As stated in the comment above, I am unsure whether 'type' is correct. Maybe I should use the plural form 'types' because I want to say that I have developed many different heuristic algorithms (not only one)
    – PeterBe
    Apr 14, 2020 at 17:51
  • The reason Decapitated Soul used a 'comment' when they said this is probably that they considered finding supporting references would be pretty tricky. But such references are required when posting such a claim in an 'answer' on ELU. Apr 14, 2020 at 18:52
  • 1
    It is matter of correctly identifying the subject. Verbs have to agree with the subject. This it can be a) ...the most common type is...., or b) ...the most common types are....
    – Ram Pillai
    Apr 19, 2020 at 7:32

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