1. 2.3 Rules in phonology
1. Sequential rules
2. Assimilation rule
3. Deletion rule

2. 1. Sequential rules Lead-in /k/, /b/, /l/, /i/
The possible words: blik, klib, bilk, kilb
The impossible words: lbki, ilbk, bkil, ilkb
The rule of /l/: if a word begins with a /l/, then the next sound must be a vowel. It is true with the rule of sound /r/ in the words like read, rape, rail, etc.
The patterning of sounds in a particular language is governed by rules. The phonological system determines which phonemes can begin a word, end a word, and follow each other.

3. 1. Sequential rules
Sequential rules: A possible word in English is one that contains phonemes in sequences that obey the phonotactic constrains of the language , that is, the rules govern the combination of sounds in a particular language .

4. 1. Sequential rules
If three consonants should cluster at the beginning of an English word, the combination should follow the sequence below:
(1) the first phoneme must be /s/;
(2) The second phoneme must be /p/, /t/, or
/k/;
(3) The third phoneme must be /l/, /r/, or /w/ Eg
Strict [strikt] splendid [‘splendid]
Scream [skri:m] square [skweə]

5. 2. Assimilation rule Lead-in E.g. A. cap [kæp] can[ ] tap [tæp] tan[ ]
B. tent [tent] tenth [ ]
ninety [naɪti] ninth [ ]
C. since [sins] sink [siŋk]
mince [mins] mink[miŋk]

6. 2. Assimilation rule
Assimilation rule----assimilates one sound to another by “copying” a feature of a sequential phoneme, thus making the two phones similar.
e.g1. the prefix in is pronounced differently when in different phonetic contexts:
indiscreet alveolar [ * d]
inconceivable velar [ *k]
input bilabial [* p]

7. 2. Assimilation rule E.g2. beam, green, team, scream
[i:] sound is nasalized, because the sound in all these sound combinations is followed by a nasal [n] or [m].
E.g3. the negative form “in”
inpossible , impossible
The [n] sound is assimilated to [m], which accounts for the right spellings of the words like implausible, illegal, and irregular.

8. 2. Classification of Assimilation
同化现象可分为临近同化和非同化，根据先后顺序，也可分为逆同化和顺同化。鼻音化、齿音化及软腭化都是同化现象。
In terms of the distance between the target and the trigger, assimilation falls into two types: contiguous assimilation and non-contiguous assimilation.
Contiguous assimilation includes two subtypes: partial assimilation as in “ten bikes/ten plays” and total assimilation as in “ten mice”.

9. 2. Classification of Assimilation
Non-contiguous assimilation can be showed in “discussing shortly”.
Assimilation can also be divided, according to its direction, into progressive and regressive types.
If the target is followed by the trigger, the assimilation is regressive as in “ten bikes”; if the target is preceded by the trigger, the assimilation is progressive as in “branch school”.

10. 2. Classification of Assimilation
Assimilation of neighbouring sounds is, for the most part, caused by articulatory or physiological processes.
When we speak, we tend to increase the ease of articulation.

11. 3. Deletion rule
Deletion rule---- it tells us when a sound is to be deleted although it is orthographically represented,
e.g. design, paradigm, there is no [g] sound; but the [g] sound is pronounced in their corresponding forms signature, designation, paradigmatic.
The rule can be stated as: Delete a [g] when it occurs before a final nasal consonant. The deletion rule also accounts for the regular deletion of the sound represented by the letter b in words like tomb, comb, and bomb. Why?

12. Topic for discussion
What are the three criteria linguists use to group allophones into phonemes?