#Python 2, (削除) 110 (削除ここまで)(削除) 87 (削除ここまで) 60 bytes

Saving 1 byte thanks to Neil

Requires input enclosed in quotes, e.g. 'KNEES'

True if it is an infinity word, False if not and it has length of 5 and prints error message if wrong length

s=input()
a,b,c,d,e=map(cmp,s,s[1:]+s[0])
print a*c+b*d|e<-1

Inspired by xnor's answer using map(cmp...

s=input()
e=map(cmp,s,s[1:]+s[0])
print e[4]==0and e[0]*e[2]+e[1]*e[3]==-2and 5==len(s)

previous solution:

s=input()
d=[ord(x)-ord(y)for x,y in zip(s,s[1:])]
print s[0]==s[4]and d[0]*d[2]<0and d[1]*d[3]<0and 4==len(d)

Using the optimized logic of Kevin Cruijssen

Python 2, (削除) 110 (削除ここまで)(削除) 87 (削除ここまで) 60 bytes

Saving 1 byte thanks to Neil

Requires input enclosed in quotes, e.g. 'KNEES'

True if it is an infinity word, False if not and it has length of 5 and prints error message if wrong length

s=input()
a,b,c,d,e=map(cmp,s,s[1:]+s[0])
print a*c+b*d|e<-1

Inspired by xnor's answer using map(cmp...

s=input()
e=map(cmp,s,s[1:]+s[0])
print e[4]==0and e[0]*e[2]+e[1]*e[3]==-2and 5==len(s)

previous solution:

s=input()
d=[ord(x)-ord(y)for x,y in zip(s,s[1:])]
print s[0]==s[4]and d[0]*d[2]<0and d[1]*d[3]<0and 4==len(d)

Using the optimized logic of Kevin Cruijssen

#Python 2, (削除) 110 (削除ここまで) (削除) 87 (削除ここまで) 60 bytes

Saving 1 byte thanks to Neil

Requires input enclosed in quotes, e.g. 'KNEES'

True if it is an infinity word, False if not and it has length of 5 and prints error message if wrong length

s=input()
a,b,c,d,e=map(cmp,s,s[1:]+s[0])
print a*c+b*d|e<-1

Inspired by xnor's answer using map(cmp...

s=input()
e=map(cmp,s,s[1:]+s[0])
print e[4]==0and e[0]*e[2]+e[1]*e[3]==-2and 5==len(s)

previous solution:

s=input()
d=[ord(x)-ord(y)for x,y in zip(s,s[1:])]
print s[0]==s[4]and d[0]*d[2]<0and d[1]*d[3]<0and 4==len(d)

Using the optimized logic of Kevin Cruijssen

#Python 2, (削除) 110 (削除ここまで) (削除) 87 (削除ここまで) 60 bytes

Saving 1 byte thanks to Neil

Requires input enclosed in quotes, e.g. 'KNEES'

True if it is an infinity word, False if not and it has length of 5 and prints error message if wrong length

s=input()
a,b,c,d,e=map(cmp,s,s[1:]+s[0])
print a*c+b*d|e<-1

Inspired by xnor's answer using map(cmp...

s=input()
e=map(cmp,s,s[1:]+s[0])
print e[4]==0and e[0]*e[2]+e[1]*e[3]==-2and 5==len(s)

previous solution:

s=input()
d=[ord(x)-ord(y)for x,y in zip(s,s[1:])]
print s[0]==s[4]and d[0]*d[2]<0and d[1]*d[3]<0and 4==len(d)

Using the optimized logic of Kevin Cruijssen

#Python 2, (削除) 110 (削除ここまで) (削除) 87 (削除ここまで) 61 bytes

Requires input enclosed in quotes, e.g. 'KNEES'

True if it is an infinity word, False if not and it has length of 5 and prints error message if wrong length

s=input()
a,b,c,d,e=map(cmp,s,s[1:]+s[0])
print a*c+b*d|e==-2

Inspired by xnor's answer using map(cmp...

s=input()
e=map(cmp,s,s[1:]+s[0])
print e[4]==0and e[0]*e[2]+e[1]*e[3]==-2and 5==len(s)

previous solution:

s=input()
d=[ord(x)-ord(y)for x,y in zip(s,s[1:])]
print s[0]==s[4]and d[0]*d[2]<0and d[1]*d[3]<0and 4==len(d)

Using the optimized logic of Kevin Cruijssen

#Python 2, (削除) 110 (削除ここまで) (削除) 87 (削除ここまで) 60 bytes

Saving 1 byte thanks to Neil

Requires input enclosed in quotes, e.g. 'KNEES'

True if it is an infinity word, False if not and it has length of 5 and prints error message if wrong length

s=input()
a,b,c,d,e=map(cmp,s,s[1:]+s[0])
print a*c+b*d|e<-1

Inspired by xnor's answer using map(cmp...

s=input()
e=map(cmp,s,s[1:]+s[0])
print e[4]==0and e[0]*e[2]+e[1]*e[3]==-2and 5==len(s)

previous solution:

s=input()
d=[ord(x)-ord(y)for x,y in zip(s,s[1:])]
print s[0]==s[4]and d[0]*d[2]<0and d[1]*d[3]<0and 4==len(d)

Using the optimized logic of Kevin Cruijssen