We are feeling experimental and want to create a new dish. There are various ingredients we can choose from and we’d like to use as many of them as possible, but some ingredients don’t go well with others. If there arepossible ingredients (numbered 1to n), we write down an matrix giving thediscordbetween any pair of ingredients. Thisdiscordis a real number between 0.0and 1.0, where means “they go together perfectly” and 1.0 means “they really don’t go together.” Here’s an example matrix when there are five possible ingredients.

In this case, ingredients 2and 3go together pretty well whereas1and5clash badly. Notice that this matrix is necessarily symmetric; and that the diagonal entries are always . 0.0Any set of ingredients incurs apenaltywhich isthe sum of all discord values between pairs of ingredients.For instance, the set of ingredients{1,3,5}incurs a penalty of 0.2+1.0+0.5=1.7

.We want this penalty to be small.

EXPERIMENTAL CUISINE

Input:, nthe number of ingredients to choose from D;,the n×n“ discord” matrix; some numberp0

OUTPUT:The maximum number of ingredients we can choose with penalty p.

Show that ifEXPERIMENTAL CUISINEis solvable in polynomial time, then so is 3SAT.

Short Answer

Expert verified

If EXPERIMENTAL CUISINE can be solved in polynomial time, then INDEPENDENT SET can also be solved in polynomial time. It is already known that INDEPENDENT SET is NP-complete.

Step by step solution

01

Statement

Remember the data:

For some high-quality regular languages, aset of rules have polynomial-timeif its strolling time is higher constrained by means of a polynomial expression within the length of the technique’s input.

The Boolean satisfiability problem, additionally known as the propositional satisfiability hassle that is abbreviated as SATISFIABILITY, SAT, or B-SAT. It is the task of finding if there may be a proof that fulfills a provided Boolean formula.

02

Step 2:Show that if EXPERIMENTAL CUISINE is solvable in polynomial time, then so is 3SAT

Consider that the EXPERIMENTAL CUISINE is a generalization of INDEPENDENT SET.

To identify an independent set whose sizeisin a graph G=(V,E),construct the following example of the EXPERIMENTAL CUISINE problem with n=|V|ingredients.

Consider penalty p=0and let the discord between ingredient iandjbe 1 if (i,j)Eand assume that it is zero otherwise.

ingredients can be selected with a total penaltyp=0 if there is an independent set of size s.

Hence, if EXPERIMENTAL CUISINE can be solved in polynomial time, then INDEPENDENT SET can also be solved in polynomial time. It is already known that INDEPENDENT SET is NP-complete.

Therefore, if INDEPENDENT SET can be solved in polynomial time, then every problem in NP can be solved in polynomial time including 3SAT.

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Most popular questions from this chapter

Sequencing by hybridization. One experimental procedure for identifying a new DNA sequence repeatedly probes it to determine which k-mers(substrings of length ) it contains. Based on these, the full sequence must then be reconstructed.Let’s now formulate this as a combinatorial problem. For any string x (the DNA sequence), let Γ(x)denote the multiset of all of its localid="1658905204605" k-mers. In particular, localid="1658904556515" Γ(x)contains exactly |x|-k+1elements.The reconstruction problem is now easy to state: given a multiset of strings, find a string x such that Γ(x)is exactly this multiset.

(a)Show that the reconstruction problem reduces to RUDRATA PATH. (Hint: Construct a directed graph with one node for each localid="1658904858295" k-mers, and with an edge from a to b if the last k-1characters of match the first localid="1658905395287" k-1characters of b.)

(b)But in fact, there is much better news. Show that the same problem also reduces to EULER PATH. (Hint: This time, use one directed edge for each k-mer.)

STINGY SAT is the following problem: given a set of clauses (each a disjunction of literals) and an integer K , find a satisfying assignment in which at most K variables are true, if such an assignment exists. Prove that isNP -complete.

Determine which of the following problems are NP-complete and which are solvable in polynomial time. In each problem you are given an undirected graph G=(V,E), along with:

(a)A set of nodesLV , and you must find a spanning tree such that its set of leaves includes the set L.

(b)A set of nodes LV, and you must find a spanning tree such that its set of leaves is precisely the set L.

(c)A set of nodesLV , and you must find a spanning tree such that its set of leaves is included in the set L.

(d)An integer k, and you must find a spanning tree withk or fewer leaves.

(e)An integer k, and you must find a spanning tree withk or more leaves.

(f)An integer k, and you must find a spanning tree with exactlyk leaves.

Show that for any problem in NP, there is an algorithm which solves n in time O 2pnwhere is the size of the input instance and p(n)is a polynomial (which may depend on ).

Show that the following problem is NP-complete.

MAXIMUM COMMON SUBGRAPHInput: Two graphs G1=(V1,E1)and G2=(V2,E2); a budget b.Output: Two set of nodes V1'V1and V2'V2whose deletion leaves at leastb nodes in each graph, and makes the two graphs identical.

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